I'm not a fan of discounting my commission. I don't want to get into a discussion of what I charge, but suffice it to say that I don't discount.
I do reduce my fee for repeat business, family and close friends... but otherwise, I charge my full rate.
But when asked if I'll discount... I have been known to offer a perk of some kind. One of my favourite perks will be "I will offer a bonus if in addition to listing with me, I will give you a $500 gift card if you purchase with me, as well".
Or, I will give you a restaurant gift card if you'll refer a new client. I have given a free car wash 5- or 10-punch card for clients with nice cars who've purchased with me.
People who are looking for that discount can often be mollified with a bonus of some kind.