Unfortunately I noticed almost immediately some in my circle began using the dustsweeper to give super low votes, leaving the responsibility to those they were commenting on to make it worth anything. For just that reason, I quickly stopped using the dustsweeper and they throw the small percentage away now if they vote my comment, as well as have stopped themselves from getting a vote back from me. I notice some of them might be doing it to be more active in your engagement league, and it is a shame they think they are helping themselves while creating for some of us a bad image of their interactions here.
I usually try to give a .03 upvote, although sometimes I will give the full 100% upvote for an outstanding post, or a worthy cause.
It's a shame to think that this might be the reason. The votes do not impact the score in the league as much as the majority of the metrics.
I think I missed my @dustsweeper reminder message as I also get a fair number of $0.02 votes but they aren't being topped up. $0.03 is the way to go if you can.