エクセルでは出来ないと思います。
罫線の変わりにシェイプで線を引く、
なら可能です。
マクロのサンプルです。
Sub test()
Dim i As Long
Dim c As Range
Dim si1 As Single
Dim si2 As Single
Dim tp As Single
Dim lt As Single
Dim sp As Shape
For Each c In Selection
tp = c.Top
lt = c.Left
si1 = c.Offset(, 1).Left - c.Left
si2 = c.Offset(1).Top - c.Top
Set sp = ActiveSheet.Shapes.AddShape(msoShapeRoundedRectangle, lt, tp, si1, si2)
With sp
.Adjustments.Item(1) = 0.3629
End With
Next
End Sub
お礼
ご返信ありがとうございます。