Here's how you lose the business of someone who has ordered cakes from your bakery for more than 15 years:
Woman at counter: Your total is $21.00.
Me (taking out pre-written check for $19.00, as they do not take credit cards): Oh... the woman on the phone told me $19.00. Let me see if I have some cash.
Woman at counter: No, it's $21.00. It's a $2.00 charge for the cake being marble.
Me: OK. Would the woman who took my order on the phone not have known that?
Woman at counter: I took your order, and there is no way I could've told you the wrong total. We always charge $2.00 for marble, and I always tell customers. You must have misunderstood.
Me (wondering how I would have written a check for $19.00 if the person on the phone didn't tell me that was the total): No problem, but I'm pretty sure you told me $19.00. Thanks.
Woman at counter, to fellow employee, as I'm walking toward the door: I really don't appreciate people telling me I don't know how to do my job!
Me: And I don't appreciate someone telling me they are incapable of making mistakes.
Woman at counter: [mumbles something under her breath and refuses to look up]
Me: This is how you lose customers. It's TWO DOLLARS!