function isEuropean($country) {
    switch ($country) {
        case "AD":
        case "AT":
        case "BE":
        case "BG":
        case "HR":
        case "CY":
        case "CZ":
        case "DK":
        case "EE":
        case "FO":
        case "FI":
        case "FR":
        case "DE":
        case "GI":
        case "GR":
        case "GL":
        case "GG":
        case "VA":
        case "HU":
        case "IS":
        case "IE":
        case "IM":
        case "IL":
        case "IT":
        case "JE":
        case "LV":
        case "LI":
        case "LT":
        case "LU":
        case "MT":
        case "MC":
        case "ME":
        case "NL":
        case "NO":
        case "PL":
        case "RO":
        case "PM":
        case "SM":
        case "RS":
        case "SK":
        case "SI":
        case "ES":
        case "SJ":
        case "SE":
        case "CH":
        case "TR":
        case "UK":
        case "MK":
        case "PT":
            return true;
            break;
       default:
            return false;
}
}

// Set European pricing as default
$stripe_percent = 1.4;
$stripe_fixed = 0.2;

// Check if country of card is not European. If so, update pricing
// $token is sent from your web page to your server when your user submits their card details
if (!isEuropean($token.card.country)){
    $stripe_percent = 2.9;
}

// Amount you want to keep in pounds
$amount_to_keep = 100;

$amount_to_charge = round(($amount_to_keep + $stripe_fixed) / (1 - ($stripe_percent / 100)), 2);

// Need to convert pounds to pence for API
$amount_to_charge = $amount_to_charge * 100;

// Create the charge
$charge = \Stripe\Charge::create(array(
  "amount" => $amount_to_charge,
  "currency" => "GBP",
  "source" => $token
));