Roman Cart WordPress Plugin Std easily link WordPress to a RomanCart shopping cart, no html required!
You have to enter the StoreId whenever you log into the RomanCart website. It's the exact same number that you enter into the settings page for this plugin.
You can signup for a RomanCart account for free (as at the time of writing - Apr 2014) using the following url: RomanCart Registration
Use the community support forums here on WordPress.org for the free version