When you place a bid, the Icephorm Pre-Loved site bids on your behalf an amount just high enough to beat the current maximum bid. The bid increment is the amount by which the current highest bid is raised each time someone places a higher bid.
When you sell on the Icephorm Pre-Loved site you can either use the built-in proportional increments table or use your custom fixed increment which allows you to specify how much your bid is raised each time someone places a bid.