For waitstaff at a restaurant, baristas at a coffee shop, bartenders, or people giving personalized service (for example a tattoo artist) it's customary to give

For waitstaff at a restaurant, baristas at a coffee shop, bartenders, or people giving personalized service (for example a tattoo artist) it's customary to give a tip of ~20% extra on top of the bill. The expectation is that extra money goes directly to the staff giving you the service, and you are expected to pay it; many of these services jobs are actually legally allowed to pay less than minimum wage with the expectation that the tips will cover the difference. You are allowed to give less if you feel the service wasn't satisfactory, or if it's an especially large bill, but to give no tip at all means you are a terrible person. From my experience most people working these jobs prefer the tips system the way it is because a lot of times it's in cash so they can fudge their tax numbers if they want (might not be true nowadays as less people use cash), and also because often they make more money through tips than minimum wage, and they think if tips were removed the restaurants would only pay them minimum wage.