I am updating my website so it can tell where someone is and charge them in the correct currency.
That part is basically done but I can only charge in AUD with my current bank etc.
I am going to add to the terms that all payments will be converted and charged in AUD but I need to know if there is a tool I can integrate into my order form.
Basically the way I see it work is that someone will come to the site and see the price GBP49 or USD49 or EUR49 or NZD49 etc and when they click to pay my website will query somewhere to find out how much that is in AUD and then process that amount.
What I need to know is where the somewhere might be?
Sorry, but that sounds a little off-putting. Why don't you display both prices up front, so there's no confusion. The main price would be AUD and the conversion (approx) would be in local currency. This would save the user getting a currency surprise when they use the form. By the way, how do you determine local currency if the user has reached your site via proxy server?
What I said was just an overview and all of that side is in hand... can you help with the actual conversion?
This appears to be what you are looking for - very easy to implement by the looks of it.
Alternative: google currency converter api php
I keep typing ghoogle - that's twice today, spooky or Freudian slip?
Bit late I know, but I've just finished developing a solution to this problem at http://currency.creative-dreaming.com - disclaimer, this is my product which I am selling, but I do provide all the information necessary to do it yourself.
Here is another one https://openexchangerates.org/signup
ps - its worth pointing out that both google and yahoo exchange rates aren't allowed to be used for commercial use.