When bidding with imperfect information (that is, each party does not know the other bids, only if his is the highest,) it makes sense to bid in non-even number

When bidding with imperfect information (that is, each party does not know the other bids, only if his is the highest,) it makes sense to bid in non-even numbers. I think the bidding here wasn't such, so it probably not the reason here.