Ive been on Tramadol for over a decade, and I break them in half all the time. They arent scored, so I doubt if you get exactly 1/2 a dose, But its close enough for government work, as they say lol. I wouldnt recommend doing this with just any pill though, and for sure be very careful with extended release stuff, that should never be broken or crushed.
Hope this helped.
Your Friend, Fabby