That's a lot of money, but not "change public policy" levels of cash, either.

On the other side, handling pennies is expensive for businesses and banks, I bet it costs at least that much. There are special interests on both sides of this.

I'd imagine you also have to take into account all coin to cash machines that issue gift cards for change, and take decent percentages. They probably make several orders of magnitude more than the mineral companies.

If their profit margin is around 8% or so, which I assume would be reasonable for mining & industrial firms, that's a really small amount and not worth the lobbying cost