Bartender tipping question

[2planka]

Worked late last night, the Warden was in school, so I dropped in on a local pub to have a bite and a pint or two and watch big fat David Wells throw BP to the Devil Dogs.

I ordered a Sam Octoberfest draft. The barmaid - not quite a dish but stacked - tells me that Miller Lite drafts are $1. I thank her but I'm sticking with Sam.

Four pints and some tasty $8.99 chicklin flings later, it's time to settle up. I notice that she's been charging me $1 per beer, recording the sale as Miller Lite even though I'm drinking Sam.

Total bill came to $14.92.

How much to tip?