Checkout sample on jsFiddle
http://jsfiddle.net/TdSCX/[
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You need to add event handler for checkboxes of GridView using jQuery as below
$(function(){
$('table#GridView1 tr td input[type="checkbox"]').click(function(){
var finalTotal = parseFloat($('#finalLabel').html());
var labelValue = parseFloat($(this).siblings('label').html());
if($(this).prop('checked')){
finalTotal += labelValue;
}
else {
finalTotal -= labelValue;
}
$('#finalLabel').html(finalTotal);
});
});
Replace ID GridView1 with ID of your GridView