When horse begins this? What are you or others doing? Watching, or actively asking him to quit it, either by clucking him up, or getting after him? Or does he do this regardless?
You can try, if this horse is determined to do this even with humans telling him to come up, taking a Coke can filled with some rocks, and rattling it, making him step up. Stop immediately when he does move forwards. You will need to be behind him, but not within range of hooves.
Can also use crop to tap back end, when you are at side, and tell him to come up.
He could also be taught to ground tie?
But agree he does need to hard tie. Very aggravating. Not to mention hard on items.
A word of caution though. We had a Pacific Bailey mare, 4 years old, that had been "taught a lesson about tying" and she pulled so hard and got so twisted up, that she stringhalted herself. It happened with previous owner, so no telling how they attempted to "teach her a lesson" but I do know the results. Really nice mare too.