My immediate reaction was "were" too, because of "rupees". However, I then started to think about what I would say in English about my currency.
I would use "There was ten pounds/a tenner in my pocket" because I think of it as a single amount of money. It doesn't mean I had one single £10 note in my pocket. I would say the same thing if I had a total of £10 made up of, for example, a £5 note, two £1 coins and a collection of smaller change. I would only use "were" if I said "There were ten pound coins in my pocket". In that case, I am referring to the plural "coins".
The important thing, I think, for you to consider is that in your original sentence you are talking about a total amount of money ("amount" is singular).