Linking a field to data on a website?

[Young Padawan]

I'm not sure which forum is the correct one for this question so I'll ask here. I'm making a quote program and it's being used to make quotes for Canadian, American, and British companies. I'd like to be able to calculate the current exchange rate by making a script that looks it up on a website if possible.

eg. The quote is listen in American dollars, I'd like to be able to click on a button and it would convert it to Canadian dollars at today's exchange rate.

Thanks for any help.