Like other helpers, number_to_currency should support :order.
Many languages don't have a symbol (like $, ã or â¬) as unit. but instead a currency with words that is written AFTER the number (such as the Danish "2 kr.")
I think that this patch should be considered in the same way as Bob Silvas ticket 6294 "Make distance_of_time_in_words and company localizable".
Furthermore, adding :order to number_to_currency will make it consistent with date_select that also supports :order
Note that this is not only relevant for minor countries like Denmark, Sweden, Norway, but also for east european countries like Russia and when using international currency codes, like GBP or EUR.
Background list on currencies from wikipedia: http://en.wikipedia.org/wiki/List_of_circulating_currencies
