If you want to round numbers in PowerShell, then you have two choices (at least) with slightly different results.
Let's set the stage:
PS > $a = 8
PS > $b = 6
PS > $a / $b
1.3333333333333
One way is to use the format string approach.
PS > "{0:n2}" -f ($a / $b)
1.33
So "{0:n2}" denotes a formatted string, where the 2 is how many decimal places to show. After the -f, you put your expression to format. There are other choices for this formatted string, which I will not detail here. The point is that your output is a string.
Another way is to use the Math .NET class to Round.
PS > [Math]::Round(($a / $b), 2)
1.33
This time, however, you get a Double instead of a string.
It looks like PowerShell does a great job at sorting number strings as numbers. So far, it doesn't matter which way you use above; Sort-Object puts the numbers in the right order. PowerShell even lets you do Math operations on numbers stored as strings! Isn't it great?