What do you tip chauffeur service from Chas de Gaulle airport ($75)? In general, around Paris, how do you tip taxis?
I might give the guy an extra 5E but around Paris itself I just round up, maybe an extra euro if the driver's been helpful in some minor way. Americans tip to much. We are used to waiters etc. making a living wage off tips vs. salary as an example. As a consequence sometimes (just sometimes) American's are seen as an easy mark. I mean, who wants to be that "Ugly American" right!