The New York Times had an article about bargaining for Electronics with megastores like Best Buy, Circuit City:
It appears that you can bargain at these types of places.
So why is bargaining out of fashion at a North American grocery store, but acceptable on a car lot or perhaps an electronic store?
If I hazard a guess it would be that bargaining makes more sense on big ticket items. Imagine how long it would take if I bargained on everything in my grocery cart. This is because there are fixed cost to bargaining. Second a company needs to empower employees to make deals. This works well for cars, since negotiations can be made at the reduction of the salesperson’s commission.