In Malaysia, Malaysians do not tip and they do not expect to be tipped either. Unlike the American model the Malaysian waiters receive a higher fixed basic pay.
There is a service charge of 10% as well as a 5% government tax on the bill in major restaurant establishments. However, this has never stopped some locals from leaving the loose change behind or leaving behind RM2 to RM10 Ringgit, if he is happy about the service or feels like it. This does not happen in the local hawker stall or lower establishment restaurants. The point to remember is that it is not expected.
Guides, crew from tours, bell boys or room service at the hotel where you are encouraged and if you wish to show you appreciation for a good service go for it!