AYUDA con suma de cantidades monetarias

[xempro]

Código HTML:

function Suma2(isChecked, myValue){
	myValue=myValue.replace(",","");
	var total=0;
    tot = parseFloat(document.sumar2.total2.value);
    myValue = parseFloat(myValue);

    if (isChecked)
		total = tot + myValue;
	else
		total = tot - myValue;
	document.sumar2.total2.value = total.toFixed(2);
}