IMO, if you ship globally, a currency converter is a natural tool to supply, even if the conversion is low. But there is a tradeoff between traffic, bandwith etc.
Tools that you supply on your site can IMO be very effective. Today the competition is fierce, so your tools need to stand out.
My favourite software platform back to Borland Turbo C++ has always been
C++Builder - RAD Visual Development IDE and C++ Compiler
Take a course in C++ and learn Borland C++ Builder.
It is outstanding. I don't know of a more professional platform. Start a C++ group in your neighbourhood.
It is not far from the level that you draw your program and C++ is the "portable assembler" today.