Spigot 1.12.1
MH 5.0.9-B464
HolographicDisplays 2.2.6

Display Total_Coins in hologram.
Drop and pick up moneybag.
Update hologram.
Total_Coins does not change.
No indication of added coins in database.

Total_Coins count the amount of money dropped from killed mobs, no matter if they are picked up or not. If you drop some money your self it is not counted.

Hmmm. Unfortunately, I need to know the amount picked up. If it's dropped and left, someone else can pick it up. Or eventually, it will despawn? In any event, I want to display the player balance, so I guess I'll try Holographic-Scoreboard.