title: How can I show total price at checkout page [OpenCart]
body: <p>I would like to make some calculations at the checkout page. If for example the total price of all products is 80€, I want to show a message that says: "You can add more products on cart worth of 20€, so you can get a discount which activates when total cost is 100€".</p>
  
  <p>To do this I have to get the total price as a variable and do this:</p>
  
  <pre><code>$tp = totalprice;
  
  if ( $tp &lt; 100 ) {
      $tp_less = 100 - $tp;
  }
  
  echo 'You can add more products on cart worth of ' . $tp_less . '€.';
  </code></pre>
  
  <p>The problem here is that I don't know how to get the total price as a variable.</p>
  
  <pre><code>&lt;?php echo $cart_total = $this-&gt;cart-&gt;getTotal(); ?&gt;
  </code></pre>
  
  <p>I placed the above at the file /checkout.tpl but I get an error so it's not working. Actually, whenever I use any code that has 'this' inside it I get error: </p>
  
  <p>"Notice: Undefined property: Template\Basic::$cart"</p>