KORN, actually you just need a sharp steak knife.
Hold the pill against a bread board with two fingers and that should allow enough room to place the blade right on the indention in the middle of the pill.
Apply modest pressure down (don't try and saw it in half) and it should break.
From there, just break the resulting .5 in half with your fingers.
It's not utterly precise...You might get a 1/4 piece that's a bit bigger than the other, but it's close enough so you know you're in between 5 and 10 when you take a 1/2 pill and one of the quarters.
Also, breaking down the pill causes it to then break down a bit faster in your digestive system and this might help you get desired results while taking a lesser amount.
Just took 3/4 pill. see how it goes. tiny little bastards to cut.