One way:
Public Sub RoundEverything()
Const sWRAPPER As String = "=Round(#, 2)"
Dim rCell As Range
Dim rReplace As Range
On Error Resume Next
Set rReplace = Cells.SpecialCells(xlCellTypeFormulas, xlNumbers)
If rReplace Is Nothing Then
Set rReplace = Cells.SpecialCells( _
xlCellTypeConstants, xlNumbers)
Else
Set rReplace = Union(rReplace, _
Cells.SpecialCells(xlCellTypeConstants, xlNumbers))
End If
On Error GoTo 0
If Not rReplace Is Nothing Then
For Each rCell In rReplace
With rCell
.Formula = Replace(Replace( _
,sWRAPPER "#", .Formula), "(=", "(")
End With
Next rCell
End If
End Sub