Rounding numbers in a list.

If i have a list of numbers in the domain 0-1.0, can i round them up to a set list of values? For example, I've used the same domain to create a range of numbers. They are 0, 0.25, 0.5, 0.75, 1.0. I would like my 0-1 numbers from the first list to be rounded to these values. so that everything thats between 0 and say 0.125 gets rounded to 0, 0.125-.375 to .25 and so on.