[Haskell-beginners] question about round function

Hi, This is my first time with Haskell. Here is what I found while trying out some examples : Prelude> round 3.499999999999999 3 it :: Integer Prelude> round 3.4999999999999999 4 it :: Integer --------------- Prelude> round 111111.49999999999 111111 it :: Integer Prelude> round 111111.499999999999 111112 it :: Integer Is it something to do with the CPU register size ?