Fixed Point Rounding

Hey guys,

I have one more question about fixed point rounding. If you multiply two numbers and have to perform rounding, how would you do that with fixed point? I'm currently rounding a 32 bit product down to 16 bits by truncating the first 15 bits, thus performing a division by 2^15. But, if you have four bits representing the fractional part, how do you perform the rounding?