Here is the US we have free law centers where lawyers will consult with you. Do you have that in Australia?
If not, I can move this question over to the Law area of Just Answer - but until your company does something (fire you, have you arrested) I am not sure anyone can really do anything - or give you solid advice.
For now though, just go about doing what you normally do - do not be around money if at all possible. Don't give them any reason to suspect you.
If they fire you, ask if you can resign instead, with a written letter of recommendation to take with you. That way, you can jus present that to future employers (if, of course, it comes to this), I am just trying to prepare you...
Tell them that you were just desperate - that you had nover done this before and won't ever do it again and that you are sorry. Ask them if they can just allow you to resign with a letter of recommendation and you will just leave. DO NOT say anything like, "I'll leave quietly" - you don't want to give the impression you'd sue or make an issue of it.
If they have you arrested - just cooperate. Don't say anything - just do what is asked and don't make a scene - I don't know about in Australia, but here - we have the right to remain silent until we can speak with our attorney - so you may want to have an attorney lined up (here, if we can't afford one - a free one is appointed. DO they do that there too?)
Lastly, be prepared that right now they may be building a case against you - what you say, how youact and what you do NOW may come in to play - so be aboce reproach in all interactions and behaviors.
Keep me updated and let me know if you'd rather speak with an attorney here on JA.