Convert currency from one country to another easily with Google's finance calculator, using that it's possible to collect the output using PHP.</p>

https://www.google.com/finance/converter

Altaf Hussain wrote an excellent function to collect currencies from Google finance you pass the amount, currency from and currency to be converted to.

This example below compresses the code slightly also wraps the final output inside a number_format function to keep the currency in whole number format.

<?php
function convertCurrency($amount, $from, $to){
    $data = file_get_contents("https://www.google.com/finance/converter?a=$amount&from=$from&to=$to");
    preg_match("/<span class=bld>(.*)</span>/",$data, $converted);
    $converted = preg_replace("/[^0-9.]/", "", $converted[1]);
    return number_format(round($converted, 3),2);
}

echo convertCurrency("10.00", "GBP", "USD");
?>