It is not that simple. There are no clear rules on where you tip. You have to live in the area and simply learn it. E.g. you don’t tip at Starbucks, but you do tip at most cafés, you tip you taxi driver but not your bus driver. You don’t tip at the gas station. In an open bar you are still supposed to tip the bartender even if you don’t pay for the drinks, but hardly any guides tell you that. If there is live music sometimes you are supposed to tip them, but you can never tell when.