How can use round in a macro to get rid of the decimals???

Give this a try:

Sub roundNumbers()
    Application.ScreenUpdating = False
    Dim rng As Range
    For Each rng In Range("B:B")
        If rng.Value <> "" Then rng.Value = Round(rng, 0)
    Next rng
    Application.ScreenUpdating = True
End Sub