Depending on how you formatted the cells, you might consider

Tools>Options>Calculation tab, check Precision as displayed. Look in HELP to read the consequences.

One way:

   Public Sub WrapARound()
       Const sWRAPPER As String = "=Round(#; 0)"
       Dim ws As Worksheet
       Dim rFormulae As Range
       Dim rCell As Range
       For Each ws In ActiveWorkbook.Worksheets
           On Error Resume Next 'in case no formulae
           Set rFormulae = ws.Cells.SpecialCells(xlCellTypeFormulas)
           On Error GoTo 0
           If Not rFormulae Is Nothing Then
               For Each rCell In rFormulae
                   With rCell
                       If Not .Formula Like "=ROUND(*" Then _
                           .Formula = Replace( _
                                       sWRAPPER, "#", Mid(.Formula, 2))
                   End With
               Next rCell
           End If
           Set rFormulae = Nothing
       Next ws
   End Sub