Any amount of Steem Power will make a difference, it just might not be enough of a difference to add up to $0.01. The most my vote can possibly be worth at this moment (assuming 100% voting power) is approximately $0.89. This means that each Steem Power can have a maximum vote worth of about .00052. That means you need at least 20 additional Steem Power to add an extra penny to your vote.