As already previously discussed in this question, its answer and comments the currency tag is as ambiguous as they get.
This is the tag description:
usefulness of this tag is under debate If your question is about whether a saying or usage is currently in active use, consider using contemporary-english.
If your question is about money, consider keeping this tag, or using only other tags that categorize your question.
See this Meta question for the discussion.
We can see that even the description is rather unhelpful and advises already against using it.
In the previous meta question two mods and everything that's up-voted agrees on using the tag contemporary-english for everything regarding the currency of use and the tag currency for questions regarding money. For further clarity AndrewLeach suggested using the tag money and make currency a synonym.
Thus, I suggest a two-pieced approach.