The round count is how much you have on hand when you start tracking usage with the app. You don't decrement the round count when you shoot some, unless you didn't track it with a firing set.
The "round count" in the ammo page doesn't decrement automatically when I enter a firing set, but I do need to manually increment it when I buy/make more ammo, right? That's why I was asking if it's a grand total of all of that particular round that I've ever bought/made, because that's how it appears to behave.
And thanks for the tip about the scrolling fields and the "collapse keypad" button - can't believe I missed that.