The Fair Work Commission routinely discounts awards of compensation for unfair dismissal where the employee has contributed to the dismissal by his or her misconduct, or indeed any other relevant contributory factor.
Here is an extract from a case which explains the approach.
“The Parties were unable to assist me with any useful precedents for how the amount of reduction should be calculated other than by reference to principle. I note that in Cowan v Sargeant Transport Pty Ltd 22Bissett C reduced the quantum by 30% for an act of public urination. Incorrect forklift operation and swearing reduced compensation by 15% in Tabro Meat Pty Ltd v Heffernan, 23 and in Van Den Enden v Bechtel Construction (Australia) Pty Ltd24 SDP Richards reduced compensation by 50% even though the wide-ranging misconduct did not warrant summary dismissal. Other recent examples include Bowden v Ottrey Homes – Cobram & District Retirement Village Inc T/A Ottrey Lodge:25 inappropriate Facebook use, breach of confidentiality of workplace investigation (20% reduction); Walsh v Ambulance Victoria:26 failure to discharge duties (50% reduction); Mora v QUBE Pty Ltd:27 injury suffered on account of work health and safety breach (50% reduction); Cronin v Choice Homes (Qld) Pty Ltd:28 inappropriate language and misuse of email (20%). This is by no means a comprehensive review, but indicative of the range of reductions for misconduct of varying types and seriousness.”
Mahoney v Bechtel Constructions  FWC 6294 delivered 10 September 2014 per Booth C
And see also Chapman v Tassal Group Limited T/A Tassal Operations Pty Ltd (2017) FWC 4630 delivered 7 September 2017 per Barclay DP