function updateTotal (obj) {
	var amount = obj.amount
	
	for (i=0; i< amount.length; i++) {
		if (amount[i].checked) {
			
			if (amount[i].value == 'other') {
				obj.charge_total.value = obj.amount_other.value
			} else {
				obj.charge_total.value = amount[i].value
			}
			
			return true;
		}
	}
	
	return false;
}