title: How to apply discount after tax programatically for a Magento 2 order?
body: <p>I have created an order programatically in Magento 2.
  I am provided with data:</p>
  
  <ul>
  <li>Item value: $10</li>
  <li>Tax Rate: 20%</li>
  <li>Discount: $2</li>
  <li>Grand Total: $10</li>
  </ul>
  
  <p>Now taxes are inclusive product prices, so by default in Magento 2:</p>
  
  <ul>
  <li>Item price: $10</li>
  <li>Item price after discount: $8</li>
  <li>Tax: 20 % of $8 = $1.6</li>
  <li>Grand Total : $8 + $1.6 = $9.6.</li>
  </ul>
  
  <p>Grand total is not same as provided.
  I want to add discount after tax calculation.</p>