Commission Advise on 10k sf retail in Newark NJ

[Achi Adamit]

My company built a brand new 13k sf retail in Newark NJ. For 10k sf we have a 15 year solid offer from a publicly traded medical company. However, broker who has exclusive with tenant is seeking commission equal to 5% of net aggregate of the deal (including renewals, extensions, expansions) which will come out to approx $250,000 -- which is a lot of money for the owner. 

My question to owners: What have been your realistic brokerage agreements for deals like these? What average figures would I use to negotiate down the broker?

My question to agents: What is a typical leasing commission structure in this area for a deal like this, and what is the lowest you'll generally accept in order to consummate a deal?