In the United States tip is usually not included in the price. The staff employed in the service sector earn a low average salary and they rely on tips. For this reason you should not fail to express your satisfaction in the amount of tip given. Usually 15% - 20% of the invoice price are given depending on the garde of satisfaction.
Who should get a tip?
At the Airport:
Porters: $ 1 per bag. If you have an electric-vehicle $ 2-3 per person are common.
Shuttle bus driver receive a tip if they help with the suitcases: $ 1-2 per bag.
A taxi driver or limousine driver should receive a tip of 10% -15% if he "only" drives. If he also assist in loading and unloading of luggage and is otherwise helpful 20% of travel costs are reasonable.
In the hotels:
The doorman should receive for unloading the baggage $ 1, for very heavy luggage $ 2
If someone takes care of your luggage from the hotel entrance to the reception and then to your room, then he should get $ 1 and for heavy luggage $ 2
If you stay several days in a hotel, then put the maid $ 3-5 per night, in luxury hotels $ 6-10 per night clear visible on the pillow. Only in this way it's obvious that it is a tip.
Room service employees receive 15% -20% of the invoice, if it's not yet on the bill. The concierge does not expect a tip for recommendations and advices, but usually gets $ 3-5 for reservations at the restaurant, $ 20 to arrange tours, $ 25 for organization of concert or theater tickets, which are difficult to obtain. Staff at the pool receive $ 2-5 for service, like bringing chairs or towels.
Valet Parking: Someone from the restaurant, hotel or shopping center parks your car and bring it back. In addition to the normal fee, the staff expect a tip of $ 1-2, usually after they returned the car.
Restaurants: The service receives 15% -20% of the bill.
Bar: If you spend the entire evening at the counter at a bar, then you give a tip like the table service personnel (15% -20% of the bill). If you order only one drink, then give 15% up to $ 1 per drink.
The hairdresser should receive a gratuity in any case, depending on the frequency of visiting with the barber shop, the service and satisfaction are 20% reasonable.
There are also areas where employees not expect a tip. This includes personnel in self-service restaurants, support staff in restaurants or shop clerks. Even the staff in the supermarkets who pack your groceries and even bring all your purchases to your car, don't receive a tip.
The list of tip recipients seems long, but mostly you get a great and friendly service. Should you not be satisfied, then do not hesitate to remind the manager on it.
All above mentioned figures can only be a recommendation. You always decide for yourself how much tip you want to give.