I long ago established some hard rules for myself as far as how much I am willing to spend for certain foods. Despite inflation, I have not changed these limits since setting them about ten years ago. Though these are strict rules for me, you may find them to be useful guidelines when you are at the grocery store. If something costs more than my limit, I just don't buy it. There are many foods that I can only buy when they are on sale, and I have found that foods go on sale often enough that I do not go deprived of the foods I like. I often find food for less than my limits. I shop at a regular Albertson's chain store for most products.
Steak (rare occasions)- $5.00/lb (I am still sometimes able to get tenderloin and T-bones)
Chicken breasts, boneless, skinless - $2.00/lb
Cereal - $2.00/lb
Cheese - $4.00/lb
Mushrooms - $3.00/lb
Carrots - $1.00/lb
Onions - $1.00/lb
Tomatoes, canned - $1.00/32oz
Pineapple, canned (Dole) - $1.00/20oz
Yogurt (Danon Light & Fit or Yoplait only) - $0.085/oz
Granola Bars (Kashi or Nature Valley) - $0.50 ea.
Orange Juice (Tropicana only) - $0.05/oz
Spices - $1.00/1.3oz (buy these at a drug store or hardware store; not McCormick)
I do go to Trader Joe's for a few things, and I am lucky that one is very close to me. They have very inexpensive all natural peanut butter, honey, tea, tree nuts, fine cheeses, and chocolate.
Besides those limits, I tend to buy things only when they are on sale, but without strict limits in mind. Canned vegetables, tuna, potatoes, bagged salad/spinach, fish, bacon (typically buy 1 get 2 free deals). Once or twice per year I've been able to buy 101 fl oz jugs of extra virgin olive oil for $10-12, which is a steal. Every once in a while canned veggies are 42-50 cents per can, and I stock up. A small local market sometimes has grapefruit 6/$2, so that's when I get to eat grapefruit. I make my own bread, which is fun and cheap; yeast comes in an $8 jar that can make approximately 32 loaves or 48 pizzas. I love the summer for berries, and the fall for apples and squash. Local, seasonal foods are better quality and the prices are reasonable even to me.
Some prices are rising and causing me to reconsider my shopping behaviors with regard to them. Brown rice, which I can only find in 2lb bags, is getting more expensive. It's up to $2.50 per bag now, and I've been using barley as a replacement in some meals. Canned tuna is rising, so I bought piles of it the last time it was $0.50/can, and I don't think I'll ever see that price again. I will gradually adapt to changes in the market, but always strive to optimize my grocery habits.