We had public holidays last week so some answers must wait. This issue of yours is not a simple one to solve. It will take a few days to find a solution. If you want to refund pls send an email to sales@koolreport.com.

Pls try this:

<script>
    var groupAmount = {};
</script>
<?php
DataTables::create(array(
    "name" => "myTable1",
    "dataStore" => $this->dataStore('sales'),
    "columns" => [
        "customerName", "productLine", "productName", 
        "dollar_sales" => [
            "type" => "num-fmt",
            "render" => "function(data, type, row, meta) {
                var customerGroupName = row[0]; // because group field 'customerName' index is 0
                var customerGroupAmount = groupAmount[customerGroupName];
                return (type !== 'sort' || customerGroupAmount === undefined) ? 
                    $.fn.dataTable.render.number( '.', ',', 0, '' ).display(data) : customerGroupAmount;
            }"
        ],
    ],
    "clientRowGroup" => [
        "customerName" => [
            'direction' => 'asc',
            'calculate' => [
                'totalSales' => [
                    "sum",  // sum, count, avg, min, max 
                    "dollar_sales",
                    "format" => "function(agg) {
                        groupAmount[group] = agg; // save group amount of this customer group
                        return agg;
                    }",
                ],
            ],
            "top" => "<td colspan='999'>{expandCollapseIcon} Top: Customer: {customerName} | Total: {totalSales}</td>",
        ],
    ],
    "options" => [
        "paging" => false,
    ],
    "onReady" => "function() {
        myTable1
        .order( [ 3, 'desc' ] ) // sort 'dollar_sales' field, index of which is 3
        .draw();
    }",
));

Pls post your full DataTables' create code.

I see that you set "paging" => true. Pls note that DataTable's client row group only groups the rows in the current page. If you change page, the total amount changes, too. It's advisable to set "paging" => false when using client row group. If the problem remains, pls share a screenshot of the problem and mark where it is in the screenshot.

It looks like the total amount is sorted by string instead of formatted number. Pls try to change your amount's type to the following to see if it works:

                "amount" => [
                    "label" => 'Amount',
                    'formatValue'=>...,
                    "type" => "num", // num-fmt, html-num, html-num-fmt
                    "render" => ...,
                ], 

Pls send a sample of your data and your report's code to support@koolreport.com for us to replicate this problem and fix it for you. Tks,

We received your attachment and found that if you set "ordering" => false then the amount column can not be ordered. It explains why your groups can not be ordered by the total amount. Pls try to set "ordering" => true in DataTables' options and see if it solves the problem for you.

In case you don't want to enable ordering for other columns you could set them like this:

    ...
    "options" => [
        'columnDefs' => array(
            array(
                'orderable' => false,
                'targets' => [0, 1, 2, 3], //disable ordering option for the 1st, 2nd, 3rd and 4th columns
            ),
        ),
        'ordering' => true, 

Next time please clarify exactly and specifically how sorting doesn't work. It looks like group amount sorting works fine now that "ordering" => true. Only the row sorting in each group hasn't worked yet. Pls try this method:

                    "amount" => [
                        "formatValue" => function($value) {
                            return "$" . $value;
                        },
                        "type" => "num-fmt",
                        "render" => "function(data, type, row, meta) {
                            var customerGroupName = row[0]; // because group field 'customerName' index is 0
                            var customerGroupAmount = groupAmount[customerGroupName];
                            var numData = data.replace('$', '') * 1;
                            return (type !== 'sort' || customerGroupAmount === undefined) ? 
                                $.fn.dataTable.render.number( '.', ',', 0, '' ).display(data) : (customerGroupAmount * 10000000 + numData ); // use 10000000 multiplying here if your data is always less than 10000000. Otherwise increase to 10000000000
                        }"
                    ], 

My previous answer works in most normal cases but there're some edge cases which would invalidate it. For a better solution pls use this:

        <script>
            var groups = [];
            var groupAmount = {};
            var groupOrder = {};
            var amounts = [];
        </script>
<?php
DataTables::create(array(
    ...
    "amount" => [
        "formatValue" => function($value) {
            return "$" . $value;
        },
        "type" => "num-fmt",
        "render" => "function(data, type, row, meta) {
            var customerGroupName = row[0]; // because group field 'customerName' index is 0
            var customerGroupOrder = groupOrder[customerGroupName];
            var numData = data.replace('$', '') * 1;
            return (type !== 'sort' || customerGroupAmount === undefined) ? 
                $.fn.dataTable.render.number( '.', ',', 0, '' ).display(data) : (customerGroupOrder * 100000000000 + numData );
        }"
    ],         
    "clientRowGroup" => [
        "customerName" => [
            'direction' => 'asc',
            'calculate' => [
                'totalSales' => [
                    "sum",  // sum, count, avg, min, max 
                    "amount",
                    "format" => "function(agg) {
                        if (groups.indexOf(group) == -1) groups.push(group);
                        groupAmount[group] = agg.toFixed(0); // save group amount of this customer group
                        amounts = [];
                        for (var p in groupAmount) amounts.push([p, groupAmount[p]]);
                        amounts.sort(function(a, b) { return a[1] - b[1]; });
                        amounts.forEach(function(amt) { groupOrder[amt[0]] = amt[1]; });
                        return agg;
                    }",
                ],
            ],
            "top" => "<td colspan='999'>{expandCollapseIcon} Top: Customer: {customerName} | Total: {totalSales} | Count distinct line: {countDistinctLine}</td>",
        ],
    ],
    "options" => [
        'ordering' => true,
    ],
));