The price of STEEM changes by the minute (maybe even second) and is calculated on a 7 day average. So if someone were to vote for your post and brought it up to a cent, if the 7 day average of STEEM were to go down, your cent might end up at 0. Inversely, if you had a cent and the price of STEEM went UP, your one cent could turn into 2, or maybe even more. Hope that helps :)
Thanks