You are able to increase your bid at any point in the auction. 

In order to increase your bid, return to the item listing and enter a new bid amount. Enter your new price, click on update and your new bid is registered.

All bids are entered "per container" with the total owed for the complete lot shown on the bidding page.

(Eg. a lot of 50 containers, for which you bid $800. per container, will show the total owed for success of the auction of $40,000.) Increasing your bid per container automatically adjusts your "total owed" information.

Any bid placed in the last few minutes of an auction will extend the ending time of the auction by another three minutes.