There are actually several ways this can be handled in the game currently (and you always have the option of simply not confronting Robert about the issue of the money if you really want him to keep it).
When you deliver the news to Bertia about the sheep, she will take off before you can tell here about the money. Once you visit Aureus's office and witness the encounter between he and Bertia, Bertia will head back to her sheep-stand. Once she gets back there, you can speak with her again and (at that point) choose whether or not to return the gold.
I agree with Hiver, an option to let say "On second thought, you can keep the money" would be appreciated.
I'd also like Bertia's end reworked so you have the option to give her the money before telling on Roberts, or keep the money and just tell her who stole the sheep. If you pay her off before, she does NOT tell Aureus, if you just tell her who stole the sheep but don't pay her, then she runs off, and you lose the chance to pay her. Make it a case of greed versus doing the right thing. I assumed that there was no way to pay Bertia off because she always ran off to Aureus. It was NOT intuitive to think that you had to return to her afterwards.
The big draw of the Divinity series in general is their questing, and they often have multiple ways to solve them. Only having one way things can go is less than ideal. I wonder if the later game quests will have the same problems.
