mark ups vary
Mark ups vary, and mark ups are what most stores call their profit. Profit is the purpose of business, without it, free enterprise would fall apart.
The least markup ? Groceries 3-5% max, they make it up in volume, Newspapers only have 2 % markup. Stereo stuff actually only has 10% or so markup, and computers have very little. Furniture can be marked up 100%, and diamonds and other jewelry have a markup of over 300%. If I could remember my source, I'd cite it, I just remember stuff like that.