Bids must be at least 5% higher than the previous bid. Only bids in the same payment token (e.g. wrapped ETH or DAI) as the auction will be counted towards the winning bid.
If someone bids in the last 10 minutes of an auction, and if their bid exceeds all others, the auction will automatically extend by 10 minutes. Cancellations to the top bid also trigger an extension. This can continue for up to a week of extensions.