I am having the same problem. I am in South African and I am using the Paypal standard option. I found out I was getting conversion errors (ZAR to US) because of my code being wrong. I changed it and there are no more errors except that it is still doing the same thing. Say my item price would be R200 (ZAR) then on paypal checkout it would say $200 (US) which would lead to the client paying R2000 (ZAR) instead. I have tried everything. I don't know what to do anymore to fix it.