Currency conversionj for PayPal

I have online tutoring website in joomla with appointment booking pro (ABPro) component. I want to receive payments by PayPal. My currency is Croatian kuna (HRK) that is not supported by PayPal. I want to display prices on pages in HRK and convert them into Euro before sending it to PayPal. Problem is ABPro. I have contacted the developer and he mentioned a way to go. It is about changing displayed currency and amount rather than simple conversion before sent to PayPal. You will need to: - change the the Euros to HRK in the display and calculation routines - then change the displayed HRK back to Euros to send to PayPal. as suggested, or whatever to resolve this. The problem is also that information is picked up from several files in javascript, php... So, you will need to have good programming skills.