Below is a way to iterate through all open drawings and save, close and do other things. There has to be a better way to do this, but this was the easiest at the time.
[CommandMethod("DwgScale10", CommandFlags.Session)]
public void sveDwgScale10()
{
int i = 0;
Document curDoc;
DocumentCollection docCol;
docCol = Autodesk.AutoCAD.ApplicationServices.Application.DocumentManager;
foreach (Document doc in docCol)
{
docCol.MdiActiveDocument = doc;
Editor ed = Autodesk.AutoCAD.ApplicationServices.Application.DocumentManager.MdiActiveDocument.Editor;
doc.SendStringToExecute("scale all 0,0,0 10.0 ", false, false, true);
doc.SendStringToExecute("zoom e ", false, false, true);
doc.SendStringToExecute("qsave ", false, false, true);
doc.SendStringToExecute("close ", false, false, false);
}
}