Wait no this doesn't make sense. It's not an 8th decimal of a pound, it's an 8th decimal of what you're measuring. If you're measuring out a pound of Carfentanil you might be off by 0.05mg, but if you're measuring a dose you'll actually take, you won't.
It's ounces, grams and kilos in that business, but the ounces are an old-school unit that's dying out. You might buy an "ounce" of weed, but an ounce of cocaine is ridiculous unless you're Charlie Sheen.