data structure for currencies exchange

What's the best data structure for currency exchange?

The exchange rate goes something like this:
1 Euro = 1.3552

First I was going to use double, but then I thought this class could do better:

Code:

---

class CurrencyAmount{
  public:
      // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      long long number;
      int permillion;
      // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
};

---

So I don't have to deal with floats. permillion will never exceed 1 mil in value.

But would double be good enough for this?

Floating point types cannot exactly represent powers of 0.1 (decimal), or several multiples thereof.

You do the math ...... how many times will you want to multiply by a decimal fraction?