I am confused by what you are asking but lets take a stab.

Ebay has a policy where tying bids earlier go to the bid that is placed earlier.

if, Pete and his opponent both bid $15 even then the win would go to Pete because his bid was in first.

However since his opposing bidder had $15.01 which was placed later and Pete had $15, when it came to that last bid between them the proxy server(?) bids in increments of the two bidders high bids.

Assuming .50 for over $10 and that we are beginning at $4.99 instead of $5 that would bring us to,

13.99
14.49
14.99
Pete still has 1 cent left so
15
and his opponent had 15.01

It would be a bit to recreate the whole bidding cycle so I would assume that pete may have had the 14.49 and his opponent had the 14.99. With the bids being pre posted, that would take the remainders of their bids to be played. Thus Pete gets 15.00 and the other guy the 15.01. Since the bids were PRE-Posted they would be allowed. However if a NEW bidder entered he would have to enter his bid at a .50 increment.

Another example why an odd, off amount, bid can be helpful as it allows you to win with less than another full increment of bid. Thus if a sniper comes in with a last second bid they can get awefully close and you can still win because your bid was a previous bid.

Hopefully that makes it a little clearer?