Tax and service charges are always included in bills for everything from restaurant meals to taxis, but tipping is common, even if it is only a little extra 'rounded up' to the nearest appropriate unit. For a cup of coffee for example, it's cents, but 10% or so is pretty common for lunch and dinner. Waiting staff are paid a living wage, so this is a question of manners rather than anything else, but it is nice to show appreciation of good service, and it's best to leave the tip in cash. Although not precisely a tip, you will often pay to use the toilet in department stores and large cafes (20-50 cents). There are no public facilities in Amsterdam. If your taxi driver has been extra helpful, you may like to add another 10% or so.