My father changes his story often, but the most common version is that for his particular hunt; all gratuity was given to the PH. The PH then distributed it to his trackers, drivers, etc...
The PH received a tip of a couple hundred dollars for himself, I believe, plus about a hundred rounds of ammunition. (Would have been a Weatherby rifle as tip, but that ended up being payment for another animal.... long story, not relevant here.)
However, bringing up the rifle does lead me to this:
If you intend to use a rifle as tip or payment for your hunt; talk to the PH before you even go. Certain countries won't allow it. Certain PHs don't want it. Certain countries don't allow specific calibers/cartridges to be in the hands of locals. Also, certain Professional Hunters may be insulted if you try to give them a rifle in an odd-ball caliber, a caliber in which they can't get ammunition (even though it may be easy for us), or a caliber in which they have 17 rifles.
Lt. Dan may have some more advice on the subject.