If you are trading the US market, how do you calculate the buy & sell price converted to AUD for tax? Do you just use an exchange rate from xe.com for the buy/sell date? If so, take this scenario:
Day 1 - buy stock ABC @ $20 with $1 AUD = $0.50 USD
Day 2 - sell stock ABC @ $20 with $1 AUD = $1 USD
You've bought & sold the same stock at the same price but the exchange rate doubled the 2nd day. You haven't made a profit/loss but then you use the exchange rate of each day & for tax purposes you've "made" a 100% profit???