My rule of thumb is that at a bar, if a beer costs less than 6 or 7 dollars, it's a $1 tip, more than that $2. Cocktails get a bigger tip, depending on the complexity of the drink, but typically land somewhere around the 25% rounded up to the dollar mark.

If you're on a tab, you tip at the end, but a slightly larger cash tip on your first drink will get you much faster service the rest of the evening.

They were tips on free whiskey/vodka + mixer as we were gambling. I googled at the time and those numbers were recommended for that service. For food drinks etc would normally tip 15-20% depending on service, would also go lower if it was terrible.

In Vegas, that $3 beer would cost $15 anyway, if you weren't getting it for free at the tables.

Depends on where you're at and the cost of living in the area. Its about making sure the people serving you are recognized as people and not slaves