Bulk order discount

[AndrewOrf93]

I'm brand new and i'm wondering what kind of discount is normal to offer on a bulk order when they arise. 

(fake scenario)

I pay $10 per unit of cereal (its expensive cereal) and they pay $12 per unit but decide to order 750 units what would a normal %  be as far as discount. 

Assuming most of us are hitting the same profit margins what would be a fair rate?