I used to do that too :( A lot! Not because I didn't want to give more, but because my vote was literally less than .02 until last month. I used to give out votes thinking that I'd be helping someone at least earn a few cents but nope! I was just wasting voting power and being symbolically nice. :P
However, those votes do help when they add to other votes. Three people with 0.01 can give someone a few cents of rewards!
They are also useful for moving comments around, some up, some down.
:p
:PP