Selected Answer
You can use the formula below to round the numbers you have in column L. Copy it to row 2, in any column of your worksheet and copy down as required.
=ROUNDDOWN((L2*2),1)/2
If you are looking for a VBA solution, the procedure below will appply the same formua to all values in column L.
Sub RoundDown_ColumnL()
Dim Tmp As Variant
Dim Rl As Long
Dim R As Long
' Better: replace ActiveSheet with Worksheets("[Tab name]")
With ActiveSheet
Rl = .Cells(.Rows.Count, "L").End(xlUp).Row
' presuming that the first value to round is in row 2
For R = 2 To Rl
With .Cells(R, "L")
Tmp = .Value
If IsNumeric(Tmp) Then ' skip if value isn't a number
.Value = Application.WorksheetFunction.RoundDown(Tmp * 2, 1) / 2
End If
End With
Next R
End With
End Sub
You might embed the above in a larger program that opens and closes a particular workbook. As you correctly point out, such code could be contained in another file, perhaps an add-in, which would require still further managment. That you would have to set up first. If you have questions about that they are unrelated to this thread and can't, therefore, be dealt with here.