I use my computer to help me find what's on sale. I have bookmarks to the online ads of several of my local grocery stores. But I've found a site that is even easier to use. It's Cairo.com, a dumb name for a useful site.
No signup is required. You put in your zip code and a keyword of what you are looking for. Simple is best. 'Toilet paper' or 'rice' or 'beans'. You'll get a price and an image of what's on sale. They seem to have all the stores around here listed, at least the major ones. It's very useful and keeps you from wasting that expensive gas going from place to place.