I've never asked a Hertz agent to drive me to the terminal. I've never inferred that this would automatically be offered, mainly because I wouldn't assume Hertz was staffed to do it. These days, they often seem understaffed to process returns timely as it is.

However, if it was available at all, it seems like something that would be free (or maybe a small charge...$5 or whatever), plus tip. If it was free and I really wanted it, I'd probably tip $10 for it. If it's $25, I'm simply not going to use it unless it's an emergency, and I'm unlikely to tip at all on top of that.