// Currency conversion rates have to be available in the target currency 
$fromCur = 'USD'; // currency code to convert from - usually your base currency
$toCur = 'EUR'; // currency to convert to
$converted_final_price = round(Mage::helper('directory')->currencyConvert($tax->getPrice($product, $product->getFinalPrice(), false), $fromCur, $toCur), 2);