I know that D&D as written was intended to be as much about resource management as anything else. Really, when you think about it, 10 coins to a pound might make for easy math, but the ability to move with your loot was practically nil. You needed 40 pounds of gold just to buy a suit of plate mail.
So, of course, encumbrance was one of the first parts of the game we houseruled in high school. Not intentionally, we never discussed it, but the sheer weight of coinage made it something we just stopped counting towards weight. Heresy, I know.
Later, bags of holding and portable holes gave us an in game reason to no longer fret about coins. Drop them into an inter-dimensional space and be done with it.
Later still, we changed it to 100 coins per pound, but even that didn't satisfy.
These days, my groups trade in coins for gems, but really, who else but a gem merchant or jeweler is ever going to cash them out?
How do you handle the heavy coins of classic D&D?