It's poor strategy to do so, as it gives other people a chance to decide whether they want to outbid you.
Best strategy is to bid your maximum amount in the dying seconds, if that's still enough - if someone was happily sat below their max, and didn't increase because they were "winning", you can grab it off them for less than if you had both fought for top spot throughout the auction.
Of course, if everyone bids their maximum amount when they notice the auction, sniping like this becomes irrelevant. But people don't, because they're people. I like that they're acting like people when I'm selling things. I dislike it when I'm buying things (because they push the price up by fighting for the top spot days before the end.)
