Sometimes the 'capping' can be unintentional too, like people...

Sometimes the 'capping' can be unintentional too, like people throwing a heap of sell orders all in at 20c on GDN until the numbers look insurmountable to the standard punter.

You learn to ignore the large sells, and say that in all likelihood, they are just trying to buy more stock at 19.5c and stop it running too hard and fast on one day until a certain group have as many as they want.

If you start attacking (buying into) the price level where the large sells are stacked and they withdraw, chances are they were false sells anyway.
Another tactic might be for the cappers to sell a few at the lower level, again to make people think it's hit its top price for the day while they actually buy more as they encourage traders to sell.