I never use currency, because in our applications we need to be conscious about when we round intermediate results. Currency prevents this and frequently forces you to use NTOM() and MTON().

From a historical perspective: Most European developers got burned when they used currency about ten years ago when the Euro was introduced. Law requires that all calculation involving Euro and the former currency have to be done wit six significant digits. For the German currency that meant 5 significant decimal places, six for the Irish Pound.