Tipping is an accepted practice in New York City and you are expected to tip for almost services rendered. The general guideline seems to be 20% of the price of the service rendered.
Restaurants
While dining at a restaurant most New Yorkers tend to double the amount of the tax component of the bill and add this amount as the tip. If, however, you are dining in a group of five or six diners, New York City restaurants usually add a 20% gratuity amount to your check.
Taxis
If you are using a yellow cab to get into Manhattan from JFK airport you usually have to pay a fixed amount of $45 to which is added the toll amount (usually $5) and the tip amount (an additional $5 is appropriate). However if you plan on using a car service to or from the airport you may be expected to pay 20% as that is the amount that they expect. For trips around the city, 15%-20% is expected, with the minimum being $1.
Beauty Salons
At salons you are expected to anyone who renders a service to you. This includes even the shampoo girl/boy who washes your hair as you wait for it to be cut or highlighted. At salons as well the 20% rule works well. For the person who shampoos your hair, normally $2-$3 will suffice.
Doormen and Supers
The doormen who man your apartment building tend to help you with luggage and packages and have to be tipped accordingly. Similarly if the Super (most New York City apartment buildings have a person who is in charge of general maintenance who is known as a Super) does any repair or maintenance work in your apartment he has to be tipped.
Delivery Men
If you get food or any furniture or any other product delivered to your apartment then you are also expected to tip this delivery man and the amount depends on the type of product delivered. It could be $2-3 for the pizza to $20 to the man who delivers a piece of furniture.
Bartenders
If you are out drinking at a bar and are seated at the bar counter itself, then it is customary to tip the bartender either with every drink that you order (a $1 bill will suffice) or to add a tip to your check at the end of the night–20%.
Christmas bonuses and tips
At Christmas time you are expected to tip or pay a bonus to anybody who has rendered you services year round. If you have a part-time housekeeper who comes in to clean your apartment once a week then this individual should be given one month’s wage as bonus at Christmas time this also holds good for full time housekeepers. You are also expected to tip all the staff in your apartment building including the doormen, the super and other maintenance personnel. The amount given as tip of course depends on the type and quality of service rendered. Similarly your dry cleaner, hairdresser and anyone else who renders you regular service needs and expects to be tipped at Christmas time.