singular vs plural - Zero rupees or zero rupee on the note?

5th Pillar is an NGO fighting against the corruption in India. As a part of non-cooperation movement against corruption, it has come up with a zero rupee note. Here is its image:

Now, my question is: Should we write 'zero rupees' or 'zero rupee'? 'Zero rupee' is written everywhere in the site.

Answer

Good question!

If you are talking about the word to be printed on the note, it should be 'rupees'

Zero Rupees

Why? Because 'zero' is plural (it has been discussed thousands of times that why 'zero' is plural; Some say that 'only 1 is singular in English', others say it is grammatically synonymous with 'not any'; ...and so on; some simply raise a question -why we say 0.5 apples?...anyway, I won't get into it).

And I consider that you already know how to refer that note [you wrote 'a zero-rupee note'].