function NormalizeCurrency(Price) {
  Price = Math.round(Price*100)/100;
  Price = Price.toString();
  if (Price.indexOf('.')==-1) {
        return Price+ ".00"
  } else if(Price.indexOf('.')==Price.length-2) {
                return Price + "0"
         } else if(Price.indexOf('.')==Price.length-1) {
				return Price + "00"
		} else {
				return Price
		}
}

function CalcLoanMonthly(v_price,term,annual_interest) {
  if (annual_interest <=0) {
	return (v_price/term);
  } else {
	var interest = annual_interest/1200;
	return (v_price*Math.pow(interest+1,term)*interest)/(Math.pow(interest+1,term) - 1);
  }
}

function CalcLeaseMonthly(v_price,term,annual_interest,residual) {
  if (annual_interest <0) {
	return 0;
  } else {
	var interest = annual_interest/2400;
	return ( ((v_price+residual)*interest)+((v_price-residual)/term) );
  }
}

function calculate_monthly(){
  var price = document.form1.price.value-0;
  var sales_tax =  document.form1.sales_tax.options[document.form1.sales_tax.selectedIndex].text;
  var loan_balance = price*(1+sales_tax/100) - document.form1.loan_down.value;
  document.form1.loan_balance.value = NormalizeCurrency(loan_balance);

  var loan_term = document.form1.loan_term.options[document.form1.loan_term.selectedIndex].text;
  var loan_interest = document.form1.loan_interest.value;
  document.form1.loan_monthly.value = NormalizeCurrency(CalcLoanMonthly(loan_balance,loan_term,loan_interest));

  var lease_balance = price - document.form1.lease_down.value;
  document.form1.lease_balance.value = NormalizeCurrency(lease_balance);
  var lease_term = document.form1.lease_term.options[document.form1.lease_term.selectedIndex].text;
  var lease_interest = document.form1.lease_interest.value;
  var lease_residual = document.form1.lease_residual.value-0;
  var lease_monthly = CalcLeaseMonthly(lease_balance,lease_term,lease_interest,lease_residual)*(1+sales_tax/100);
  document.form1.lease_monthly.value = NormalizeCurrency(lease_monthly);

  return;
}