A great Mixergy interview[1] was with Herb Sorensen, author of "Inside the Mind of the Shopper"[2]. There were many fascinating revelations about the grocery business. For example, he went through the four revenue sources for grocery stores and profit on selling the goods was in fourth place, behind real estate, shelf fees, and something else I can't remember. He also explained that there is an optimum layout for a store, with counterclockwise flow.

[1] http://mixergy.com/interviews/brick-mortar-retailers-herb-so...

[2]http://www.herbsorensen.com/herbsorensenauthor.html

Pretty much it seems:

> "The average profit margin for grocery stores is 1.3 percent" says Jeff Cohen, a grocery industry analyst with IBIS World.

-- http://www.marketplace.org/topics/business/groceries-low-mar...

Average gross margin in a traditional grocery store in the US is 26-33%, depending on local competition. There is a huge range (0-90%) by product category however.

Net income after labor, distribution, and fixed costs ranges 1-6%, depending largely on market share and fixed cost control

Reference: I helped traditional retailers with price optimization for almost 20 years