When I was in Bali last month, I used the ATM to withdraw money from my Westpac Visa debit card.
Costs were
$5 per withdrawal
Using the Visa debit card to buy something, no charge (and conversion rate back to Aud appears same as rate on the day)
National Australia Bank
Withdraw funds from my cheque account, $4 plus 1% (in exchange rate)
Using Visa credit card to buy something, the NAB charge 2.35% of the purchase price.
These charges are growing steeply each year.
I s'pose we all have to live within the rules and play around them to save us.