Most people agree over how much you should tip for dinner at a restaurant.

If you ask most Americans, most of us would say 15 to 20 percent – although even here I think there can be some debate, since some people tip based on the bill including the tax and others exclude the tax from their tip calculations.

And don’t even get me started on Europeans, especially Brits, speaking as someone who used to work in a restaurant (I won’t say where) that often had a lot of British visitors. I understand waiters make more in Europe. American guidebooks are always going on and on about how you should never, ever tip more than 10 percent in England. But the message going the other way seems to have gotten lost somewhere across the Atlantic. No matter how hard we worked, no matter how great the service or the food, we never received more than 10 percent from the nicest, friendliest English people.

But if you really want to start a debate, ask people how much they think they should tip for a bottle of wine served with lunch or dinner.

Suddenly, 15 percent or 20 percent doesn’t apply for some people. Instead, I’ve read or heard people say it’s appropriate to tip 10 percent on the wine, or even simply leave a flat fee (say $10 or $20) for a bottle.