IEEE 128-bit decimal can handle a precision of 34 significant figures (decimal digits). You can store a million times the world GDP (1e6 * US$75.59 trillion) accurate to picodollars. How much more precision do you need?

The entire raison d'être of floating-point is that, unlike integers, the precision does not vary with the magnitude[1].

1. except for underflow, which reasonable financial computations never encounter, because their inputs are well-scaled.