How many people are you feeding?
Where are you shopping?
Do you have a standard grocery list?
Do you have staple meals?
For example, I feed two adult people and shop at Kroger/King Soopers almost exclusively. I have a set grocery list that I run down every time, and stock up only on what I need, or what is grossly on sale that will last/won't waste. My staple home made meals are spaghetti, chicken soup, pizza, chicken and green beans, pork chops and garlic mashed potatos, fish and vegetables, mac n cheese, etc. This is for lunch and dinner.
That being said, my tracking strategy literally is my grocery list. I always buy the same package of chicken, the same brand of apples, the same kind of garlic, the same bag of potatoes, the same brand of pasta... And I don't deviate for snacky feelings or cravings. That makes the price of the food, and the size and quality of the meals extremely predictable. If it comes down to a cost battle between two kinds of one thing, I use the "cents per ounce" marker on the price label to decide for me - cheaper wins.
Grocery bill apx $200-250/mo. Browsing the forums here has let me know I can even cut that back, if I eat less meat and more lentils. Mmm.