DevTools is a scoped application with many helpful scripts ready to be re-used.

The built-in currency conversion API object (GlideCurrencyConverter) is a bit tricky to use.

Here you can find a nice wrapper function for currency conversion based on the ServiceNow OOTB functionality:

https://github.com/saschawildgrube/servicenow-devtools/blob/master/update/sys_script_include_6f29745...