combine ranges into one peice of code create error message for rounding code

[Mikeymike_W]

Hi All,

I have the following piece of code that will round value (positive and negative values) to the nearest 0.5:

For i = 33 To 35
With Sheets(1).Cells(i, 14)
If .Value <> "" Then
.Value = Application.MRound(.Value, Sgn(.Value) * 0.5)
End If
End With
Next
For i = 12 To 21
With Sheets(1).Cells(i, 17)
If .Value <> "" Then
.Value = Application.MRound(.Value, Sgn(.Value) * 0.5)
End If
End With
Next

For i = 12 To 24
With Sheets(1).Cells(i, 19)
If .Value <> "" Then
.Value = Application.MRound(.Value, Sgn(.Value) * 0.5)
End If
End With
Next


I have it set up for a few different cell ranges so I have two question:

1) is it possible to combine these rather than having multiples

2) I want to have an error that appears so if a user enters a range of values into the cell (17-25 for example)
they are prompted to enter a single number and when they select OK the cell will be reselected

I hope you are able to help out.

Thanks in advance,

Mike