Search for cashback. It's easy to do. While shopping, simply hit the extension icon to look up offers for that store. You can save on purchases from groceries to clothes to computers. We don't offer it but provide a directory of sites that do. Click through to one of these sites and follow their instructions to get money back when you make a purchase.
Regarding permissions, this extension needs to know the URL you are browsing so that it can look up rates for that retailer. That's the only thing it looks at. Nothing else.