how to change currency display format ?

Edit product.inc.php find this function:

Code:

    function _getTextPrice($number, $currency, $startWithUpperCase=false){
        if ($number == 0.0) return $startWithUpperCase ? "Free" : "free";
        return "$currency$number";
    }

change it to

Code:

    function _getTextPrice($number, $currency, $startWithUpperCase=false){
        if ($number == 0.0) return $startWithUpperCase ? "Free" : "free";
        return "$currency".number_format($number,0,",",".");
    }