Horse Grenades, Hand Shoes, and Hit Points -- Close Enough is Good Enough

Identifying when to throw those last few hit points in the trash and call the fight a "win" for the adventurers is part of what separates a great GM from a good GM.

Your games pacing, the spotlight moment for your heavy hitters, and respecting your players time and emotional investment in a combat scene, are all much more important than the big bads last 10 HP.