Guys, I can only speak for Victoria, but most states in oz have SIMILAR provisions. As Creampuff pointed out, your conviction does NOT disappear after 10 years, whether you ask or not. It simply cannot be alledged as a prior conviction at court should you be so silly as to commit a further offence 10 or more years later. And be aware that even after 10 years, some convictions CAN still be held against you anyway.
As far as traffic matters go, they ALWAYS appear on your record in Victoria, if you have been convicted. After 10 years, a DUI conviction cannot be used against you as a prior conviction, (see above) but it always remains. Be aware too, that if you get a suspension or disqualification of your licence for speeding or demerit points, that also counts as a conviction, and is recorded for posterity. This applies whether the suspension was as a result of a penalty notice OR court hearing, there is no difference.
One last point guys, ordinarily if you are issued a penalty notice for an offence, and it does not suspend or disqualify your licence, there is no record of the penalty notice on your permanent record. The notice is kept for 3 years in Victoria to allow counting of further penalties for the period. IF you decide to fight a penalty notice at court, and you lose, and the magistrate records a conviction, you get it for good, whereas simply paying the ticket means its over and no permanent record is kept. (Instant Suspensions or Disqualifications excepted!) Hope this helps.
BTW If it helps, as I do some work in this industry, if I ask you if you have a prior conviction, however small, I expect the honest answer. Honesty counts in your favour a whole lot more than some pissy conviction I find out about later!