I just wanted to make sure this was correct:
If AUD/USD has bid ask of 0.71999/ 0.72032, that implies there is another (theoretical) pair USD/AUD which has a bid ask of (1/aud_usd_ask) / (1/aud_usd_bid) .
The reason for the theoretical pair is that if my quote currency profits are in AUD, I only have the AUD/USD bid/ask to convert back into USD and I want to make sure I have the correct bid/ask spread for the inverse pair that I'm going to use.
Ie, if I have a profit of 1000 AUD, then to convert back into USD by purchasing USD / selling AUD, I would use 1000 AUD / (1/AUD_USD_BID)
and if I have a loss of 1000 AUD, then I'd need to buy the AUD back and sell my USD in my account. For that I would use 1000 AUD / (1/AUD_USD_ASK)