A quick Google search returned ToMarket . It looks like its original purpose and design is for Groceries but you can use it for any type of item. The description says it supports bar codes and lets you put items with prices and quantity in the cart and gives you a final total. Sounds like exactly what your looking for based on the question. It looks like a nice app, I'm downloading it now for myself.
EDIT: This app is actually pretty cool, it has some default items when you first open it but if you go over to the "need" tab it is blank. When you add an item it gives quite a few details you can add to it, including whether or not it is taxable. I also noticed there is a feature to export your lists or to share it with others via SMS or email.