If you are going to need shopping card feature in your Joomla, you can use VirtueMart. VirtueMart is an Open Source E-Commerce solution to be used together with Joomla! and Mambo. Joomla! and VirtueMart are written in PHP and use MySQL environment.
It has basic shopping cart feature like adding, edit, and delete product. Pre-defined Payment Gateways like authorize.net, PayPal, 2Checkout, eWay, and Worldpay are also supported. You can use flexible Shipping Carriers and Rates Configuration.