It's a fantasy role-playing game.

DM: You are Percival de Rolo, a human gunslinger . You are the member of the famous group of adventurers. Previously, Tiberius calls for Erwen, waking him up. The dragonborn realizes that it's six a.m. and sends Erwen back to bed, saying they'll talk about it later in the day.
DM: So go ahead and make another tinkering check. And the cost of the Pepperbox should be at the bottom of your--
Player: Is it the whole cost or half?
DM: Should be half the cost. It should say under the repair rules for a misfire.
Player: Half cost. Oh my god, that's awful. Okay, tinkering check. 12.
DM: 12. Okay.
Player: Technically, that would be a success.
DM: Yeah. So you take the rest of the morning, unsleeping, the dark bags under your eyes. You manage to get the Pepperbox back in working order.
Player: Oh, I was asleep. I wasn't with them, so I just woke up really early.
DM: Right, right. But even so, even though you slept, it hasn't been very restful. It's been technically enough to rest, but your evening has been fraught with nightmares. Perpetually. But your Pepperbox is repaired, and does cost you half the cost of the weapon cost to repair.
