Fixed the bug about bidding
This branch fixes the bug where user is required to put weird values when bidding. As explained in bug report #27 (closed), using integers in database wouldn't have fixed this bug. So instead the local minimum bid is always rounded up to closest hundredth (e.g. 5.32582 -> 5.33) so it aligns with input field's "step" attribute. Note that the price is rounded UP to avoid local minimum bid being lower than actual minimum bid.