So, when I commented about the 2000 silver coins debacle, I didn't make any recommendations. Because really, who cares about whether the number seems too round?
But if I *did* care, if I really, really, REALLY wanted to make the numbers seem right, I'd record treasure amounts very roughly: "silver x10", "gold x1k". When the treasure is actually found, I'd say "you found what looks like thousands of gold coins!" Or whatever. And I'd roll 2d6 and record the round number on my session log. I'd convert this to sacks and bags as the adventurers pack up the treasure, or if they ask for an estimate of how many sacks they will need.
And when they get around to counting, I'd roll 5d6 and subtract that from the round number. Call it higher precision, call it coins lost in transit; doesn't matter.
Also: why don't we call small sacks "bags" and reserve "sacks" for the large ones? For some reason, I think of the word "sack" as implying something larger than a typical bag. Perhaps this is under the influence of my "sack of potatoes/bag of sugar" analogy.
Also also: I haven't decide how much a typical chest ought to hold. Maybe a small chest is the same as a sack, just sturdier and lockable? A trunk would be two sacks, and a coffer three sacks.