Cancelling current transaction started with $this->db->trans_start()

[eluser]teomor[/eluser]
I'm using $this->db->trans_start() to start a transaction and $this->db->trans_complete() to commit the changes, but what if I want to cancel the whole thing in the middle of it? Can I just use $this->db->trans_rollback()? Would that work on the whole transaction group?
The documentation only says to use $this->db->trans_rollback() when manually starting transactions with $this->db->trans_begin(). I'm a bit confused if this would work or not..