In my case, I need to adding shipping cost of Webshopapps Matrix Rates to cart automatically. If you meet the same requirement , you can follow these steps to make it done: 1/Create a xml file to declare new module: app/etc/modules/Inbusiness_Cart.xml <?xml version=”1.0″?> <config> <modules> <Inbusiness_Cart> <active>true</active> <codePool>local</codePool> </Inbusiness_Cart>…