I helped a buddy develop an ecommerce site in joomla using hikashop. Hikashop's cart module functionality is a bit limited. You either get a very verbose full cart or a very minimal mini cart. We customized the mini cart to include the ability to expand to the full cart in either a slider or popup. This makes the functionality similar to what you find at amazon, especially when you move the cart to the very top of the page.
The cart hidden initially because it is empty. Add an item (from those below) to the cart to have it appear. Then click the expansion image beside each to see how they expand.
Here are some demos of the expanding mini cart in action.
- Hikashop Mini Cart with Slider Demo: Mini Cart in right position that uses slider to display the full cart.
- Hikashop Mini Cart with Popup Demo: Mini Cart in right position that uses popup window to display the full cart.
- Hikashop Mini Cart at Top with Popup Demo: Mini Cart at top of the page that uses popup window to display the full cart.
If you would like to add similar functionality to your hikashop, I have packaged up the files.