=CEILING(number,0.5)
If you need to round a number up to the next half, you can use the CEILING function, which always rounds up based on a supplied multiple.
Note that MROUND also rounds based on a supplied multiple, but it always rounds to the nearest multiple.
In the example, the formula shown is:
=CEILING(B5,0.5)
Even though the value in B5 is 1.1, CEILING rounds up to the next multiple of .5, which is 1.5