Like when travelling anywhere, it is helpful to be aware of tipping etiquette and culture.  In Uganda, two areas were tipping considerations should be made regard transportation and restaurants, where practices are quite different.

Taxis, taxi-vans and boda bodas(if you are brave enough) generally don't expect tips, and always get a quoted price up front for your trip.

At local restaurants, most servers will be happy with a 10% tip added to your bill payment.  However, if you liked the server and plan on going returning to that establishment again, go ahead and tip like you would in the U.S. This will increase the odds of you having similar or even better service when you dine at the establishment again.  

The following online source offers additional general and practice advise regarding tipping etiquette in Uganda.