I think it should vary based on the service you receive. My guide stays with me from awakening until bedtime. I tip him a minimum of $20 per day. If the driver is an all day driver I give him a minimum of $10 per day. On several days tours the typical guide fee is $25 and on single day tours they charge $30. Also at the end of the trip if I have USD left, I trade the guide good bills for his bad ones.