src/Extension/ViewableCartExtension.php
public function Cart()
    {
        $order = ShoppingCart::curr();
        if (!$order || !$order->Items() || !$order->Items()->exists()) {
            return false;
        }

        return $order;
    }
public function Cart()
    {
        $order = ShoppingCart::curr();
        if (!$order || !$order->Items() || !$order->Items()->exists()) {
            return false;
        }

        return $order;
    }
Get the cart, and do last minute calculation if necessary.