Changing the subject slightly . . . if you're really trying to reduce your grocery bill, I suggest that you read the article on a food price book in The Tightwad Gazette (I think it appeared in the first edition -- she wrote three books -- and also the Total Gazette, which was all three books in one huge volume). She explains it in detail and shows how she organized hers, which is worth reading, but here's the gist of the idea:
You get a small notebook and over several months you build up a list of the items that you buy on a regular basis. Using your receipts, you write down the price of those items at each of the grocery stores convenient to you. You also keep up with the sale papers and you keep a record of when things go on sale. It'll take some effort, but after a couple months you'll figure out which stores are good for which products; this book could easily cut your grocery bill by 25%, and if you work at it it could reduce your bill much more. You'll also catch onto the pattern for when things go on sale in your area so you'll know when to stock up. Once you've figured out a pattern, you can start to plan your grocery shopping around the best prices. Perhaps this week you're planning to go to Store A, which you know usually has good meat prices -- so you plan to fill your freezer. Next week you shop at Store B, which you know is good for canned goods, so you buy a month's worth for the lowest possible prices.
Another idea for rock-bottom grocery prices . . . search out non-grocery store sources for food. It's convenient to make one stop and get everything you need, but you pay for that convenience. I shop at a food salvage store (food that was destined for restaurants, but its packaging is damaged), where I can always buy meat for $1/pound. In the summers I shop at a farmer's market; the prices are a bit better than the grocery store and the quality is much better. A friend just told me she buys salsa from On the Border restaurant, and it's cheaper than the jars at the store. I dont' buy food at Big Lots (yuck), but I do buy cleaning products there. Don't forget the day-old bread store (where the bread is NOT day-old -- go figure); I can buy three loaves of name-brand bread for $1.50. Start looking -- you'll find plenty of foods outside the grocery store.