It's a bad idea. You want to avoid oxidation once fermentation starts. After fermentation is winding down, you want the suspended proteins to fall and agitating the fermenter will work agaist both of those goals.
The only way I could see doing it is if you were using a highly flocculant yeast, and the yeast flocculated out before fermentation was finished. Perhaps a gentle swirl could encourage the yeast to finish up. I've never needed to do that, though, in nearly 300 batches of beer.