There are many situations in which customers feel the need to tip those offering a service. This can be seen in restaurants and other similar establishments, hotels, and even when riding the taxi. The tip is a sum of money with the purpose of thanking for a specifically well done job. Some people don't really know when to tip or how much, so we came up wit this to tip or not to tip: A guide to tipping in the US, to help at least some travelers out.
Tipping those who handle your bags
If you have too many bags, the staff around might determine you need some help and might carry some of the luggage. Around US, no matter where this service is offered: in an airport, at a hotel, or when boarding a ship, You should consider tipping 2 dollars for the first bag, while each additional bag will cost 1 dollar per bag. If your bags are larger, consider adding an extra dollar per bag. Add 2 or 3 dollars if the luggage is delivered to your room. It should be clear that you will not tip when you do these tasks yourself.
Tipping those who serve food or drinks
First of all, you need to determine where does the food of drinks are served: in a fast-food restaurant, at the bar next to the bartender, or at a table in a restaurant or cafe. You shouldn't worry about tipping in a fast food restaurant. All other establishments however require a tip. Table service is usually tipped between 15 and 20% of the tab. If you sit next to the bartender, he doesn't expect more than 2 dollars, but he will be more happy. Some locations have a tip jar on the counter, but not all customers use them. Regulars are more likely to tip though.
Tipping the staff at the hotel
The hotel's concierge doesn't expect any tip, unless she helps you purchase some hard to get tickets. Should this be the case, you should leave between 15 and 20% of the item's price. The cleaning staff is generally tipped between 1 or 2 dollars at less fancy hotels and can between 3 and 5 at the fancier ones.
Tipping on the plane
When flying, you're not expected to tip the check-in staff nor the flight attendants. If you require more attention compared to the other passengers then you should be considerate enough and thank them with a small tip, but it is not mandatory. It is OK to write a thanking letter to the check-in staff though.
Tipping your driver
In some US cities the taxi driver can expect between 20 and 30% of the trip's fare as a tip, however you should only do 30% if the driver was super fast or gave you an especially nice trip. Generally, a tip of 15 to 20% is more appropriate and the practice in most cities.
Remember that only helpful people deserve a tip. Some locations have the gratuity included in the bill, so read that carefully. Speak with the management if possible when you consider the staff didn't deserve it.