try this
<script>
function calculate() {
var x1 = document.getElementById('a.qty').value;
var x2 = document.getElementById('rate').value;
var x3 = document.getElementById('amt1').value;
var x4 = x1 * x2;
amt1.value = x4;
dototal();
}
function calculate1() {
var y1 = document.getElementById('qty2').value;
var y2 = document.getElementById('rate2').value;
var y3 = document.getElementById('amt2').value;
var y4 = y1 * y2;
amt2.value = y4;
dototal();
}
$(document).ready(function () {
dototal();
});
function dototal()
{
var totals = 0;
var $dataRows = $("#sum_table tr:not('.totalColumn, .titlerow')");
$dataRows.each(function () {
$(this).find('.rowDataSd input').each(function (i) {
totals += parseInt($(this).val()) || 0
});
});
$("#sum_table td.totalCol").each(function (i) {
$(this).text("total:" + totals);
});
}
</script>