Interesting point this was I thought where the other day I was at a restaurant and it came time to pay for the bill. The person I was with was calculating the bill along with another person on what the tip should be based on the usual 10% to 15% figure. They then both came up with different numbers as one person was calculating the total before tax and the other person was calculating it with the tax included. That then brought up a debate that yo should only be calculating the tip based on the meal price itself and not with the tax included.
That makes me wonder how many people calculate it before the tax and how many do it after and whether or not it is unintentional as it is something you don’t really think about. It definitely does add up too when you think about it. As well, do the people receiving it expect to get a tip based on the before or after tax figure? Kind of amazing though at how much debate something that is supposed to be purely based on your generosity can create when it comes to money.