Hi Reena,
What you are trying to do is perfectly reasonable and fits in well with the
EJB CMT concept.
Let's say your facade session bean has an entry method named processRequest(). This is the entry method that eventually calls addCustomer() in your example.
If somewhere in the processing of processRequest(), including all of its calls to all of its helper methods, it calls the setRollbackOnly() method of the SessionContext object, all database accesses done during that method call (processRequest())will be undone. I think that's what you want.
It certainly works that way with the WebLogic server.
Good luck,
Judd Smith