I'm unsure whether my comment will be related but my household of six YAs just opened a retail store.
The higher the charisma level, the better a particular sim has been at sales and ringing up.
With high charisma, I've even seen a sim go ring up a customer without my instructions.
On the other hand, a low-charisma sim just stands there for a long time after the "go ring up" instruction, even if she's not in a convo with anyone else.
So, I haven't experienced any issues with ringing up customers so far (knock on wood), except for that one sim with Level 3 charisma.
Well, I've only played the shop for several days, so perhaps it's just a fluke.
When perusing the new Retail category items in Buy mode, I noticed that two of the new retail counters feature 2+ or 5+ Focusing decor, so I got one of those counters and placed two Hipster Hugger sofas in the shop (Tech Guru reward, +2 focus.
I really have no idea whether this is helping with customer service or not, but the focused sims seem to get distracted less.
If anyone knows about how the Focusing decor influences retail sales, please share.