Magento 2 - get current tax clas in custom module

Question

I'm trying to solve a Magento 2.1.2 bug (Tier price percentage incorrect if special price set - https://github.com/magento/magento2/issues/6923) by creating a custom module.

My code so far:

<?php

namespace Namespace\TierPricingFix\Pricing\Price;

use Magento\Catalog\Model\Product;
use Magento\Customer\Api\GroupManagementInterface;
use Magento\Customer\Model\Session;
use Magento\Framework\Pricing\Adjustment\CalculatorInterface;
use Magento\Framework\Pricing\Amount\AmountInterface;
use Magento\Framework\Pricing\Price\AbstractPrice;
use Magento\Framework\Pricing\Price\BasePriceProviderInterface;
use Magento\Framework\Pricing\PriceInfoInterface;

//Added
use Magento\Catalog\Pricing\Price\FinalPrice;

 class TierPriceFix extends \Magento\Catalog\Pricing\Price\TierPrice
 {
   const TAXNL = 1.21; // Multiply base amound with NL tax 21%
   /**
    *  TODO: make TAXNL dynamic.
    */

   // Fix for https://github.com/magento/magento2/issues/6923
   public function getSavePercent(AmountInterface $amount)
   {
       return ceil(
           100 - ((100 / $this->priceInfo->getPrice(FinalPrice::PRICE_CODE)->getValue())
               * ($amount->getBaseAmount()*self::TAXNL))
       );
   }
 }

The module works as expected, the tier pricing discount percentage are generated correctly. However I want to make the constant TAXNL variable, so that it also works with other European tax percentages.

What is the best way to get the current tax percentage on a Magento 2 product page with tier pricing?

I've tried addding Magento\Tax\Model\TaxCalculation to the __construct method but this didn't work.

Answer 1

This is what I did, trying to solve this Magento 2.1.2 bug:

public function getSavePercent(AmountInterface $amount)
{
    $tax = $amount->getAdjustmentAmounts();
    $sumarTax = $tax['tax'];
    return ceil(
        100 - ((100 / $this->priceInfo->getPrice(FinalPrice::PRICE_CODE)->getValue())
            * ($amount->getBaseAmount() + $sumarTax))
    );
}

It works until they found a right solution