Is it possible to completely fail a message if the rewrite rules fail?

It depends on what you mean by fail a message and what addresses you are rewriting. If you are rewriting recipient addresses for your local domain, you can do:

*@dom.ain  ${lookup{$1}dbm{/wher/ever}{$value}{failaddr}}  Ehq

and in your alias file put something like

failaddr:   :fail: Rewriting failed

This fails a single recipient - others are processed independently.