This is an old post, but as far as I know, nothing has changed - or rather what has changed that the vote has to be even higher since only half goes to the author. So, if you vote on a comment, you need to either vote with a higher value - enough to get a payout to the person you are voting for - or they need to have dustsweeper.

https://steemit.com/steemit/@thedarkhorse/your-2-cent-vote-is-worthless-the-real-deal-on-dust-votes