$3, $5, or $7 maximum. It depends on what you feel is a good tip and how the driver treats you. Tip the driver if he helps you with your bags, explains things to you along the way, or leaves you alone if that is what you prefer. Drivers depend HEAVILY on tips, but they know they must earn them, much like waiters. In the end, you can tip whatever, if you want, and whomever you want.