Variable Commissions

I would like to request the ability to adjust the commission rate based on the following.

#1 listing site:  why?  different sites charge less than others.  also when direct booking costs less.  

#2 payment by check:  why?  could adjust 2-3% since not paying cc fee

#3 special offers:  we often find ourselves lowering our commission to make a sale.  setting tags for 1% 2% etc. at booking level would make this easier

Thank you for your consideration

Randy 

Happy Crab Vacations