On longer rides I keep a light, cheap cable lock with me, so even if I go into a store, I lock it up to something inside, like a newspaper rack, pole, or whatever I can and still keep it out of the way and something heavy or big enough so somebody can't easily walk away with my bike.

I don't think most people care, especially the employees getting paid $7/hour, and if they do, they're too busy looking at my package.