There is an additional charge added by UPS for processing an ASD--I believe it is $5.
Ground and 3-Day Select have a $5 surcharge. All flavors of NDA and 2DA do not -- for now.
If you go to a UPS Store, you'll pay the regular UPS rate. If you go to any other non-UPS run store, you will pay extra fees.
The regular UPS base rates. Keep in mind that any accessorial charges (declared value, rural surcharges, HI & AK surcharges, signature requirements, COD, etc.) may have a mark-up that can differ from TUPSS to TUPSS.
ASO's mark-up from their cost. Theoretically they don't have to (nor does TUPSS have to charge full UPS rates, either), but if an ASO is not marking-up to more than retail counter rates, they're not covering any operating margin (aka, overhead costs, labor costs, etc.).
Personally, I find it quite odd that there is no UPS employee discount on shipping. There's got to be one heck of a story behind that one.