Random numbers help please

Hello.

I want to return a random whole integer between 0 and 4 for a 1:5 ratio of returning one of these numbers.

I currently use Math.round(Math.random()*4; Since flash will round the result, 0-3 will occur more often because the can be rounded to from a higher or lower number, while 4 can only be rounded up too… Does that make sense?

So, how do i get an even ratio of 1:5?