assuming the car is in your name, when you get to the airport very early, with a lot of money to pay your fines and the fines for not paying your fines . It will all come up on the computer when you hand over your passport.
they will then check with other state authorities , which will of course take time. Oh , I forgot , you have a plane to catch ,

.
If you get away with it here , and are heading to the US , they may, and have been known to, send you back on the next available flight to sort it out in Australia.
I would really recommend you ring the traffic people in the state where you got the fine , check if there any others and get em paid. so you can leave with ease. .
I know how you feel , its the camera traps that get me every time.
I have arrived at an international airport and been aske d to pay a fine that I didnt know about , before I leave