Option Explicit

Private MODE As Integer

Sub sample()
    Dim s As String
    
    s = "12.25"
    MODE = 1: MsgBox (RoundEx(s, 1))
    MODE = 2: MsgBox (RoundEx(s, 1))
    MODE = 3: MsgBox (RoundEx(s, 1))
    MODE = 4: MsgBox (RoundEx(s, 1))
    
    s = "12.35"
    MODE = 1: MsgBox (RoundEx(s, 1))
    MODE = 2: MsgBox (RoundEx(s, 1))
    MODE = 3: MsgBox (RoundEx(s, 1))
    MODE = 4: MsgBox (RoundEx(s, 1))

End Sub


Function RoundEx(ByVal strNumber As String, ByVal intDigit As Integer) As String

    If Not IsNumeric(strNumber) Then
        RoundEx = ""
        Exit Function
    End If

    Select Case MODE
    Case 1 '切り下げ
        RoundEx = WorksheetFunction.RoundDown(strNumber, intDigit)
    Case 2 '切り上げ
        RoundEx = WorksheetFunction.RoundUp(strNumber, intDigit)
    Case 3 '四捨五入
        RoundEx = WorksheetFunction.Round(strNumber, intDigit)
    Case 4 'JIS丸め
        RoundEx = Round(strNumber, intDigit)
    Case Else
        RoundEx = strNumber
    End Select

    If intDigit > 0 Then
        RoundEx = Format(RoundEx, "0." & String(intDigit, "0"))
    End If

End Function