This is often used in charity events with many items auctioned simultaneously.
The auction is "silent" in that there is no auctioneer selling individual items,the bidders writing their bids on a bidding sheet often left on a table near the item.
At charity auctions, bid sheets usually have a fixed starting amount, predetermined bid increments, and a "guaranteed bid" amount which works the same as a "buy now" amount.
The highest bidder pays the price he or she submitted.