Sorry, I didn't express myself well...I need to convert currencyes to an payment accepted currency...
Just done with this little snippet
$app = JFactory::getApplication();
$currencyClass = hikashop_get('class.currency');
$paymentCurrencyId = $currencyClass->get($this->payment_params->payment_currency)->currency_id;
$orderCurrencyId = (int)$app->getUserState(HIKASHOP_COMPONENT.'.currency_id', $currencyClass->mainCurrency());
$totalInPaymentCurrency = $currencyClass->convertUniquePrice(round($order->cart->full_total->prices[0]->price_value_with_tax, (int)$this->currency->currency_locale['int_frac_digits']), $orderCurrencyId, $paymentCurrencyId);