Tipping

Do you usually leave a tip?  How much are you supposed to tip different people?  Is tipping common in your country?  Why is it important to leave tips?  Can you think of jobs where tipping is an important part of the salary?  When are some times you shouldn't leave a tip?  When was the last time you left a tip for someone?  How much do you usually leave for a tip?  Would you leave a tip even if you thought the waiter or waitress didn't seem to work for it?  Do you depend on tips for your income?  What is the largest tip you have ever left?  What is the largest tip you have ever received?  Do you feel uncomfortable leaving tips? Why?  Can you think of some places where tipping is required?  Can you think of some places where tipping is optional?  Can you think of some places where tipping is not necessary?