Recently we upgraded in our point of sale software the staff performance metrics, so I suggest that you take another look at it.
You will find it in register reports
Now pick in the staff section the following report
Now what I suggest you do is print the report out for a year to get a feel of what it can do for you. What you will see is a detailed listing of what each of your employees has done for your business. Most important check the profit figures out. If you export it into the Ad-hoc reports, you can also use it to track average transaction value, profit and average basket size for each person. This will help you to identify ways to increase these measures.
If you use this report daily, weekly or monthly sales targets. You can use this report for goal setting and budgeting as you can track everyone individual performance.
Also, another use is that as the report would be in real-time, you can evaluate who is busiest and so you can adjust your staffing levels accordingly.
Enjoy and see how you go!