Honestly, in my opinion, I would advise you to focus your energy on your sales and not on the discounts. I am finding more and more that wasting my time looking at eBays smokescreen, I mean "dashboard", is nothing but a marketing lure that only a few sellers ever cash in on regularly. Instead of aiming for "discounts" that only eBay can tell you if you are good enough for, (they will never give you accurate proof to back anything up when it comes to your DSR scores), instead aim for great sales and customer service. Then when the discounts do come your way, then it's just an added bonus.
If eBay wanted to give fair discounts based on your DSR's, then they would give them out to all sellers whose DSR's averages are above eBays average in the dashboard. But if they did that, then they would be losing way too much money.
Again, in my opinion- there is not a seller out there that offers more honest and timely item description, customer service and communication, faster shipping or more economical shipping than I do (I ship daily, and many of my more expensive listings all offer free shipping). Last month I got a 20% discount, and this month a 5% discount. Unless you are selling nothing but low priced items and lots of them, you will rarely see consistant discounts.
I guess that what I've come to terms with lately, is that I work for myself, not eBay. I choose eBay as one of my venues to sell some of my product, and I am very happy to do so. I just won't get caught up in their bogus reward programs or incentives anymore. I used to, but not any more. If the discounts are there, I will gladly take 'em, but I will not get fixated on them. It took several other Powersellers and a bunch of experience to help me understand the above, and come to terms with being happy selling for myself, and not for eBay.
Cheers,
AXE