public function getTax($price, $product = null, $productClass = null, $pref = null, $country = null)
    {
        /* @var $TaxRule \Eccube\Entity\TaxRule */
        $TaxRule = $this->taxRuleRepository->getByRule($product, $productClass, $pref, $country);

        if ($productClass) {
            if ($productClass->getTaxRule() != null) {
                $TaxRule = $productClass->getTaxRule();
            }
        }

        return $this->calcTax($price, $TaxRule->getTaxRate(), $TaxRule->getCalcRule()->getId(), $TaxRule->getTaxAdjust());
    }