[math]::Round($number * 2, [MidpointRounding]::AwayFromZero) / 2
Round a number to the nearest half (.5).
PS C:\> $number = 3.64285714285714 >> [math]::Round($number * 2, [MidpointRounding]::AwayFromZero) / 2 3.5
[math]::Round($number * 2, [MidpointRounding]::AwayFromZero) / 2
DetailsPS C:\> $number = 3.64285714285714 >> [math]::Round($number * 2, [MidpointRounding]::AwayFromZero) / 2 3.5