Hm, not bad at all. I rate it 8/10, with potential for more.
The protagonist is an unusual combination of cynical and easy-going.
He's been downtrodden so much that he just has no shame anymore, he simply rolls with everything.
Like, when the androgynous royal wizard flirts with him, the MC just goes "Eh, I'm not picky."
When he's confronted with the Standard Adventurer's Guild Thug, he flatters his way out of it.
The author is intelligent and gives some focus to details; lots of isekais feature store managers, this is the only one that bothers to show the actual managing of a store.
The story is only at chapter 2 at the time of writing, but if it continues like this, it's only a matter of time before it does something worthy of a 9/10 rating.
Personally I hope he does shack up with the royal wizard, it'd be pretty novel...
(They're 80% going to turn out to be a girl, though - the artist isn't being very subtle.)