Fixed it for you. :)

It puts not tipping the wait staff in a whole other light; I've only ever done that twice - both well deserved in my view.

I actually had the additional pleasure of explaining to one of those folks that, yes, I did fully understand both that it was customary to tip 15%, and that the IRS was going to tax him as though I had - but that I didn't intend to give him a bean over the bottom line on the bill - and I wanted him to think about that. :)

That's because you don't tip bartenders in the UK.

But I've never known a single bartender to refuse your offering to buy them a drink. Which, often, they choose to "save for later".