Is a tax title sale a "bid-up" or "bid-down" style auction?

It is a "bid-down" style auction in which bidders competitively bid down the percentage of an undivided ownership interest in the subject property from one hundred percent (100%) to one percent (1%). The tax collector is required to sell the least quantity of the property, determined by undivided interests, which any bidder will buy for the amount of taxes, interest, penalties and costs. The purchase price is the amount of taxes, interest, penalties and costs. The purchase price does not change throughout the auction. The rate of interest on the purchase price that the winning bidder may receive upon redemption does not change throughout the auction. There are no ties. Bidders may not bid fractions of a percentage point. The lowest percentage of ownership interest bid will be the winning bid. If there are multiple winning bids, the first to reach the winning bid will be the winner at the conclusion of a tax title sale auction.