As a general rule the higher the feed rollers are set on the planer table the more likely that the last bit of the board will be sniped as the wood moves off of the first roller and is levered upward toward the cutter head. Table rollers vary from planer to planer.
If you were to lower the table rollers all the way down so that they were below the table surface, then the friction of the wood as it travels across the planer table would generally make feeding the wood through the planer much more difficult. However this does reduce (and can sometimes eliminate) sniping.
One practice I've seen used to reduce sniping, and thus general waste on a project, is to lower the feed rollers to the same level or below the planer table and then apply a liberal coat of paste wax to the planer table. The wax reduces the friction enough that most planers can then feed the wood though the planer without jamming. If you carefully support the boards on the out feed side of the planer the then you should see a reduction on sniping on light cuts.
Heavy cuts on any but the most industrial planers will still result in some sniping as the table and or cutter head can undergo some 'loading' under a heavy cut. However if you make your last few passes taking off < 0.005" per cut then you can nearly eliminate the snipe by lowering the table rollers and waxing the planer table. It can take some practice but a very aggressive snipe can usually be prevented in my experience.
Note: never use silicone based lubricants around the shop, or in this case for lubricating a planer table. They are pure evil.