Datatable sum column by row grouping and show sum result at the end of each group

cse111

I am using datatable row grouping from https://datatables.net/examples/advanced_init/row_grouping.html and it works fine.

I have scenario as shown in image:

Now I want to calculate sum(sub-total) by each grouping abd show result in row at the end of grouping as you see in image.

At the end of listing , want to show a final row of total amount. How to accomplish that.
Js code used is

$(function() {
    var table = $('#table').DataTable({
    "columnDefs": [
        { "visible": false, "targets": 1 }
    ],
    "order": [[ 1, 'asc' ]],
    "displayLength": 25,
    "drawCallback": function ( settings ) {
        var api = this.api();
        var rows = api.rows( {page:'current'} ).nodes();
        var last=null;

        api.column(1, {page:'current'} ).data().each( function ( group, i ) {
            if ( last !== group ) {
                $(rows).eq( i ).before(
                    '<tr class="group" style="background-color:#F5F5F5;"><td colspan="3">'+group+'</td></tr>'
                );

                last = group;
            }
        } );
    }
    });
});

cse111

The image is