PHP: Calculate VAT on a price and round to two decimal places

<?php
/*Usage:You want to calculate 17.5% VAT on a price of �4.67
$price_without_vat = 4.67;
echo vat($price_without_vat);
This would return the new amount with 17.5% added, and would be rounded to 2 decimal places*/
function vat($price_without_vat)
 {      
$vat = 17.5; // define what % vat is
$price_with_vat = $price_without_vat + ($vat*($price_without_vat/100));
// work out the amount of vat       
$price_with_vat = round($price, 2);
// round to 2 decimal places      
 return $price_with_vat;      
}?>