adding up form values and disabling non numeric and decimal keys

[zippynz]

Hi, I am using this script to add up the contents of a form, It works great except it won't accept a decimals input.
That is because a friend disabled all other characters, what I need to do though is enable the decimal key so it will allow you to enter a decimal,

thanks in advance

function add(){ 
	var form = window.frmMain;
	form.Total.value = parseFloat(cBlankToZero(form.cents20.value)) + parseFloat(cBlankToZero(form.cents50.value)) + parseFloat(cBlankToZero(form.dollar1.value)) + parseFloat(cBlankToZero(form.dollars2.value)) + parseFloat(cBlankToZero(form.dollars5.value)) + parseFloat(cBlankToZero(form.dollars10.value)) + parseFloat(cBlankToZero(form.dollars20.value)) + parseFloat(cBlankToZero(form.dollars50.value)) + parseFloat(cBlankToZero(form.dollars100.value));
}

function numericOnly(){
	if (window.event.keyCode < 48 || window.event.keyCode > 57){
		window.event.returnValue = false;
	}
}

function cBlankToZero(x){
	if (x==&quot;&quot;)
		return 0;
	else
		return x;
}

 

[zippynz]

anyone?
anyone at all?

 

[zippynz]

nevermind i figured it out myself

function numericOnly(){
	if (window.event.keyCode < 46 || window.event.keyCode > 57){
		window.event.returnValue = false;
	}
	if  (window.event.keyCode == 47){
		window.event.returnValue = false;
	}
}