[MicroBob]

Nate, yes the cabbie is probably out of line.
And I hate having to tip for something like a cab-ride.
But the instant I read your post and saw that you are tipping $1.20 for a $6.80 cab-ride I thought, "Wow. Even I'm not cheap enough to do that."

I never asked anyone about it but I think the default minimum is around $2....even if the ride is only $6 or $7.

Yeah, so it's a high percentage for a tip. Big deal.
Valet-parking or getting a drink in a casino are free so if I tip $1 or $2 then I ended up tipping a percentage of infinity compared to the cost of the service.

So some of this stuff seems a bit out of whack.

$2 tip felt far more appropriate to me and not a single cabbie had to tell me.

I'm not much of a cab-rider though and I got more experience doing this in LV than any other place.
Maybe I was way over-tipping? I actually wondered that at the time.
I simply concluded, "there's no way I should only tip $1.20 or something for a $6.80 cab-ride. That just feels way too cheap to me. $2 tips it is!!" (or $2.20 or $2.40 or whatever some of the time).

I would probably also tip $3 for an $11 or $12 ride but wouldn't feel quite as bad if I only gave $2.20 or something on those I don't think.
Partly depends on friendliness/jerkishness factor and/or my own mood I guess.