Here's a code snippet that toggles the C/C++ editor's tab size between 2, 4 and 8:
' Author: Roger Karlsson
' http://rogerkarlsson.com/blogs/programming/toggle-tab-size/
Public Module ToggleTabSize
' Toggle the C/C++ editor's tab size between 2, 4 and 8.
Sub Toggle()
Dim props As EnvDTE.Properties = DTE.Properties("TextEditor", "C/C++")
Dim ts As EnvDTE.Property
Dim ins As EnvDTE.Property
ts = props.Item("TabSize")
ins = props.Item("IndentSize")
If ts.Value = 2 Then
ts.Value = 4
ins.Value = 4
ElseIf ts.Value = 4 Then
ts.Value = 8
ins.Value = 8
Else
ts.Value = 2
ins.Value = 2
End If
End Sub
End Module