title: Prestashop 1.7 total calculated incorrectly
body: <p>I'm running an online store using Prestashop. I always try to keep the software up-to-date, using the one-click update module (currently running 1.7.4.2). But one of the last updates introduced a problem: The total in the shopping cart and on checkout are not displayed correctly when using a discount code.
  <a href="https://i.stack.imgur.com/iXUNT.jpg" rel="nofollow noreferrer">image of the shopping cart with a discount code</a></p>
  
  <p>As you see in the picture, the discount is calculated correctly, but the total isn't. Here's the cart-summary-totals.tpl of my theme:</p>
  
  <pre><code>{block name='cart_summary_totals'}
  &lt;div class="cart-summary-totals"&gt;
      &lt;span class="label"&gt;&lt;strong&gt;{$cart.totals.total.label} {$cart.labels.tax_short}&lt;/strong&gt;&lt;/span&gt;
      &lt;span class="value"&gt;&lt;strong&gt;{$cart.totals.total.value}&lt;/strong&gt;&lt;/span&gt;     
  &lt;/div&gt;
  {/block}
  {block name='cart_summary_tax'}
  &lt;div class="cart-summary-line"&gt;
      &lt;span class="label sub"&gt;&lt;small&gt;{$cart.subtotals.tax.label}&lt;/small&gt;&lt;/span&gt;
      &lt;span class="value sub"&gt;&lt;small&gt;{$cart.subtotals.tax.value}&lt;/small&gt;&lt;/span&gt;
  &lt;/div&gt;
  {/block}
  </code></pre>
  
  <p>I really don't know what's causing this, and people in the prestashop forum ignore my post, so I hope I can get some help here.</p>