This Kata was definitely not a 7kyu kata. Maybe a 6kyu or 5kyu, unless the description and instructions are explained in better way (like dumb it down by a lot, lol)
You have to cast, then round, then cast. Not only that but you also have to know how to properly use each function properly and correctly type the functions, which leaves little room for possible correct answers.
In addition, you also have to figure out the ordering. The mistake I made was using GROUP BY when you are not supposed to at all for the required fields.
Regardless, I thought this Kata was supposed to teach/test me on just the ROUND() fuction, but not to the extent that this kata requires you to know (like using other functions to make it work). I'm not sure if this would even be a real world application for the use of ROUND() as well.
Once you do solve the problem, it does seem very simple, BUT just because the query looks simple, doesn't mean that the level of knowledge and application skill applies to beginners (which I believe 8kyu & 7kyu are for)
Overall, I like this kata a lot, but I believe it should be upgraded to at least a 6kyu with updated instructions/description. So my advice, is to skip it until you are comfortable with more difficult katas.

I love this answer! very clever!