You see someone rip a lipstick out of the little pack, throw the pack on the floor and put the lipstick in her pocket. It doesn't matter, you think. It costs so little that a big store like this will never miss it. You are wrong. Add a penny a pound to your potatoes.
Someone picks up a peach from the fruit counter and eats it while shopping.
He tosses the pit behind a display without thinking. Add a penny to that tomato you are considering. Even a careless change of mind cost you money. Someone went to the meat counter and selected a pack of ground beef. As they shop, they decide they do not have enough money to buy the beef, so they take it out of their cart and leave in on the nearest shelf.