Checkbox Discount Selection

Hi, Im ‘trying’ to write a checkbox type calculator. How can I do something along the lines of,

If 5 checkboxes are checked, apply a 2% discount to the total.

I am by no means an expert in javascript. I found a bit of jQuery

            $(document).ready(function() {
                var total = 0; 
     
                function calcTotal() {
                    $("input:checked").each(function() {
                        var value = $(this).attr("value");
                        total += parseFloat(value); 
                    });
                }
   
                calcTotal();     
             
                $("input:checkbox, input:radio").click(function() {
                    total = 0; 
                    calcTotal(); 
                    $("#total").val($.format('{a:.2f}', { a:total }));
                });
            });

The discounts are 2% off the total per each additional item selected. Eg if 6 items are selected then its 2% off the total, 7 items then its 4% off etc … max of 15 selectable

Many thanks

Okay this is what it looks like:

Total: £<input id=“total” type=“text” />

<input type=“checkbox” name=“Item1” id=“Item1” value=“1.00” />
<input type=“checkbox” name=“Item2” id=“Item2” value=“1.00” />
<input type=“checkbox” name=“Item3” id=“Item3” value=“1.00” />
etc…

<script type=“text/javascript” src=“…/scripts/jquery-latest.js”></script>
<script type=“text/javascript” src=“…/scripts/jquery.strings.js”></script>
<script type=“text/javascript”>
$(document).ready(function() {
var total = 0;

			function calcTotal() { 
				$("input:checked").each(function() { 
					var value = $(this).attr("value"); 
					total += parseFloat(value);  
				}); 
			} 

			calcTotal();     
         
			$("input:checkbox, input:radio").click(function() { 
				total = 0;  
				calcTotal();  
				$("#total").val($.format('{a:.2f}', { a:total }));
			});
		});

</script>

<script type=“text/javascript”>

var chkBoxes = new Array();

window.onload=function() {
var inputElems = document.getElementsByTagName(“input”);
for(var i=0; i < inputElems.length; i++) {
if(inputElems[i].type == “checkbox”) chkBoxes.push(inputElems[i]);
}
}
function calcTotal() {
var numSelected = 0;
var total = 0;
for(var i=0; i < chkBoxes.length; i++) {
if(chkBoxes[i].checked) {
numSelected++;
total += parseFloat(chkBoxes[i].value);
}
}
if(numSelected >=5) total = total*0.98;
alert(total);
}
</script>

Many thanks

Smething along the lines of this demo. You can add the extra discount calcs.

 
<script type="text/javascript">
 
var chkBoxes = new Array();
 
window.onload=function() {
  var inputElems = document.getElementsByTagName("input");
    for(var i=0; i < inputElems.length; i++) {
              if(inputElems[i].type == "checkbox")   chkBoxes.push(inputElems[i]);
    }    
}
function calcTotal() {
    var numSelected = 0;
    var total = 0;
    for(var i=0; i < chkBoxes.length; i++) {
        if(chkBoxes[i].checked) {
             numSelected++;
            total += parseFloat(chkBoxes[i].value);
        }
    }
    if(numSelected >=5) total = total*0.98;
    alert(total);
}
</script>