【Excel】VBAマクロで処理終了をメッセージボックスで通知し、いいえ（no）で連続処理を終了する方法【MsgBox, For Each, SaveAs】

Sub KeisanToHozon()
    Dim ws As Worksheet
    Set ws = ThisWorkbook.Sheets(1)
    Dim saigoGyo As Long
    saigoGyo = ws.Cells(ws.Rows.Count, 1).End(xlUp).Row

    Dim i As Integer
    For i = 1 To ws.Columns.Count
        If Application.WorksheetFunction.CountA(ws.Columns(i)) > 0 Then
            ws.Cells(saigoGyo + 1, i).Value = Application.WorksheetFunction.Sum(ws.Columns(i))
        End If
    Next i

    ws.SaveAs Filename:="ファイルパス", FileFormat:=xlWorkbookDefault
    MsgBox "処理が完了しました。", vbInformation
End Sub

Sub FolderBooksProcess()
    Dim fs As Object, f As Object, fl As Object, wb As Workbook
    Set fs = CreateObject("Scripting.FileSystemObject")
    Set f = fs.GetFolder("フォルダパス")
    Set fl = f.Files

    For Each wb In fl


        Set wb = Workbooks.Open(wb.Path)
        Dim gyoSum As Long
        gyoSum = Application.WorksheetFunction.Sum(wb.Sheets(1).Columns(1))

        wb.Sheets(1).Cells(wb.Sheets(1).Rows.Count, 1).End(xlUp).Offset(1, 0).Value = gyoSum
        wb.Close SaveChanges:=True

        If MsgBox("次のブックに進みますか？", vbYesNo) = vbNo Then Exit Sub
    Next wb
End Sub