I'm not sure I understand what you're saying. Are you saying that these exchanges are trading at prices to a precision of 10 ^ -10 dollars (or other currency)? I saw private exchanges pricing to hundredths of a cent (a long time ago - it's been a decade and half since I worked on Wall Street or in the City) or yen, but never any finer than that. Even then, all transactions were recorded in whole cents.

I'm sure you've done your homework, and I'm long out of the finance business, but even so, I think the applications where this matters are, as financial applications go, very unusual.