This will be added to as more questions are asked.
Question: If a cashier does a particularly polite and efficient job and I inform the manager of this, will it do any good?
I've done this a few times, and I hope the compliment got passed along.
It all depends on the manager. In some cases, the manager gave me a $5.00 gift card to the store, in others, I didn't find out about it until a week later and from a co-worker who was related to them.
"Mebbe not 'free', but I always say 'It's a nickel.' If it doesn't scan, it's a nickel, right?"
Usually, if an item doesn't scan, if the customer doesn't do the stupid line about it being free, I'll give it to them for a reduced price, usally about 99 cents, unless I think that price is too much. I adjust the price depending on the item and how much I like the customer.