Tips are a notorious minefield for travellers to the United States. Although technically discretionary, this is an unwritten rule that expects 15 to 20% in restaurants, the reason? The minimum wage is low in the United States and tips are therefore an important part of the income of many workers. Tips are also common in other service and hotel sectors, such as bartenders ($1 to $2 per drink), cleaning women ($1 to $5 per night), janitors (depending on the difficulty of your request), valets ($1 to $5 per person), hotel carriers ($1 to $2 per piece of luggage), doormen (a few dollars if they help you take a taxi) and taxi drivers (10 to 15%), so it is worthwhile to stock up on dollars to keep them close at hand. In a restaurant, check your invoice before giving a tip, as some restaurants automatically include a tip. If you pay with a credit card, you must enter the amount of the tip left on the credit card receipt and add it to the total.
Tips are also valid for your transfer driver or shuttle driver. Switching 10 to 15% is standard enough for a private transfer, unless service fees are already included, while shared shuttle drivers expect to receive between $2 to $3 per person.