2. Calculate the tip from the final total
This is probably something that has not occurred to many of us, but some people always calculate the tip based on the sub-total and not the after-tax total. Bartenders expect and believe it is fair to expect to be tipped based on the amount you actually have to pay. They make a good point. While it makes sense to be frugal much of time time, calculating a tip from the sub-total may be overdoing it a bit.