Tipping is an odd practice primarily because it is common and expected in some professions and not at all in others. As adults, we become accustomed to tipping in the normal day in day out activity of our business and private lives. Most adults have a tipping policy and they pretty much follow it without giving it much thought.
But when it comes to tipping on a business trips, its best to think about the use of tipping as a common courtesy in light of your business trip and how it can be used to benefit you during the trip. To do that, think about the tip as a practice and why you do it at all. For the most part we do it because it is expected.