Question about the round formula.

Hello guys :) 

I have a field with the number 4.2 and need it to round up to 4.5. 

The formula I am currently using is: 

Round([field],0.5)

But it's giving me 4.0 as an answer. 

I'm sure it's a very simple solution, but I can't figure it out. 

Any tips/help? Thanks!