JTA spec 1.1 says (assuming that Hibernate transactions should behave identically as JTA) that

An unchecked exception thrown by a registered Synchronization object causes the transaction to be aborted. That is, upon encountering an unchecked exception thrown by a registered synchronization object, the transaction manager must mark the transaction for rollback.

There's no guarantee explicitly specified that all synchronizations must be invoked, but I'd guess so...