What ATAR do you need for commerce?
Commerce and business cut-offs range widely, from about 75 to 96. Few fields have such a spread, so where you can study depends a lot on the university.
The most competitive programs, such as commerce at UNSW and Melbourne, sit near the top, often 95 or above. Many strong universities offer commerce in the high 70s to mid 80s, and business degrees at other universities can sit lower again.
The major matters too. High-demand majors like finance, economics and actuarial studies can sit above the general commerce cut-off. Actuarial studies in particular is one of the most competitive.