Round off the Decimal Values

<script type="text/javascript">

    function RoundOff() {
      var i =document.getelementbyid('txt').value;
      document.getelementbyid('txt').value=Roundnumber(i,2);
    }

   function Roundnumber(num,dec){
var result =Math.round(num*Math.pow(10,dec)/Math.pow(10,dec));
return result;

}
 
</script>