The matter of giving tips might reasonably come up in a roleplaying game. There's a wide variety of cultural tipping behaviour in the real world - compare the USA where tips are expected for a wide range of services, to Japan where tourists leaving tips are often chased down by staff to give the money back, thinking it was left in error.
It makes sense for tipping behaviour to vary at least as widely in a fictional setting with multiple cultures. Players may simply assume their own cultural habits are the norm, but you can surprise them with other expectations within the game setting. And take the opportunity to vary it! They may get used to the tipping culture in one place, only to discover that it changes radically when they travel somewhere else.
Maybe tips are expected, but have to be strictly non-monetary, due a stigma that sees offering money as akin to calling the receiver a beggar. So instead you need to have a supply of trinkets or other small, useful items to give. Or perhaps tipping of any sort is considered a bribe and can get you into legal trouble. Or tips are given as handwritten notes that may be exchanged back to the giver for a favour at a later date. Perhaps tipping is something only practised by certain rungs of society - nobles will toss money to peasants for menial jobs, but the poor never tip anyone, and it becomes an institutionalised method of redistributing wealth to the needy. Or it could go the other way - the poor need to scrape together tips/bribes to get anything done in an oligarchic bureaucracy, but the wealthy get by through their sheer power without needing to lower themselves to such behaviour.
Commentary by memnarch (who has not seen the movie)
Is 30 million credits a lot for a ship? I think 30 million credits sounds like a crazy amount for a ship. I think Luke mentioned being able to buy a ship for 15 thousand back in the original movie. Heck, even that crazy fare for just getting Han to take Obi-Wan and Luke off of Tatooine is about 3 times less than what DJ is saying here as a tip. Sure, this ride is coming from casino planet, but that's still way more than I would have thought reasonable. This has gotta be a luxury yacht or something that DJ is now not flying.
And there's the medallion again. Obviously it's not being handed over as a ride tip. So what else could it be? A symbol of some Resistance-related thing? I guess that could fit, but why have a second symbol at all? Maybe it's to demonstrate a connection to something else outside the Resistance? And then DJ actually hands it back in the movie, and that part'll just be cut out from the comic? That still has the "what's the reason?" problem, but would at least cover the bit about handing it over to begin with.
One last bit? It feels a little odd to jump so suddenly back to Rose and Finn after two comics of Rey. Or perhaps it's more accurate to say there were a few comics of Rose and Finn stuck inside the scenes with Rey. I wonder what the reason for that is. If it's how the movie scenes occurred, that makes me suspect there's a pacing problem of some kind. It doesn't feel quite right to have the action jumping around this fast when I try and think about how the movie would play out.
Transcript
GM: Let’s cliffhanger that and go back to Rose and Finn.
DJ: And DJ.
GM: Right.
DJ: Ante omnia, there’s a little matter of my tip.
Rose: Tip? You’re not even flying!
DJ: Suit yourself. Non serviam.
Finn: What’s a suitable tip? Like five credits?
DJ: Hahaha! This ain’t no junk hover-speeder. Your droid buddy hired a 30-million-credit spaceship. The fare is 50 Gs. I reckon 10% sounds fair.
Rose: Five thousand! Are you out of your mind?
DJ: Be a shame if I had to give you a bad customer review. Oh, and maybe the First Order saw it.
Finn: BB-8, give him the tip.
BB-8: I’m out. The fare was my whole winnings.
Rose: We’re gonna need every credit of what we won...
Rose: Here. Have this medallion. Haysian smelt gold. {tosses it over}
DJ: {holding Rose’s medallion} That’ll do nicely.
BB-8: Isn’t that the one matching your dead sister’s?
Rose: Yeah, our lucky charms, but Paige isn’t really into luck any more. Or breathing. Safe travels, DJ!