XL 2010 Recherche d'une fonction qui tronque un nombre décimal sans altérer la dernière décimale

=TRONQUE(A2;3)

Function tronquer(x As Range, n As Long)
   tronquer = Fix(x * 10 ^ n) / 10 ^ n
End Function

Function TronquerDec(cell As Range, nbdec As Byte)

Dim tmp$, pos As Byte, res

  tmp = cell.Text
  pos = InStr(1, tmp, Application.International(xlDecimalSeparator))
  If pos = 0 Then
    res = 0
  Else
    res = Left(Right(tmp, Len(tmp) - pos), nbdec)
  End If
  If Len(res) = 1 Then res = res * 10
 
  TronquerDec = res * 10 ^ -nbdec + Int(cell.Value)
 
End Function

Sub Essai()

Dim wf As WorksheetFunction

    [M16] = wf.TRUNC([M14], 3)

End Sub

Sub test()
dim a
   a = Application.WorksheetFunction.
End Sub

a = 1.2348
Debug.Print Evaluate("trunc(" & a & ", 3)")

Sub test()
Debug.Print MaFonction(15.3659879, 3)
End Sub
Function MaFonction(V As Double, n As Integer) As Double
Dim T As String
T = Format(V, "#0." & String(100, "0"))
MaFonction = Left(T, Len(T) - 100 + n)
End Function

Sub test()
MsgBox tronque(15.3659879)
MsgBox tronque("15,3659879")
MsgBox tronque(15)
End Sub

Function tronque(x) As Double 'ici la source (x) doit être variant !!!
tronque = CDbl(Int(x) & IIf(InStr(x, ",") > 0, Mid(x, Len(Int(x)) + 1, 4), ""))
End Function

Sub test2()
MsgBox tronque2(15.3659879)
MsgBox tronque2("15,3659879")
MsgBox tronque2(15)
End Sub

Function tronque2(x As String) As Double ' x est en string
tronque2 = CDbl(Mid(x, 1, IIf(InStr(x, ",") > 0, InStr(1, x, ",") + 3, Len(x))))
End Function

Sub test3()
MsgBox tronque3(15.3659879)
MsgBox tronque3("15,3659879")
MsgBox tronque3(15)
End Sub

Function tronque3(x As String) As Double ' x est en string
tronque3 = CDbl(Mid(x, 1, IIf(InStr(x, ",") > 0, InStrRev(x, ",") + 3, Len(x))))
End Function

Evaluate("trunc(" & a & ", 3)")

MsgBox Evaluate("TRUNC(" & Trim$(Str$(A)) & ",3)")