multiple discount coupons

I've got a series of very similar membership with different pricing, depending on who the customer is and how many people subscribe (to my workshops) at the same time.

So I need to offer more than one discount code:
e.g. let's say attending a workshop costs $100
the coupon code for a student could be STUDENT ($60)
the code for a teacher could be TEACHER ($70)
the code for attending an online webinar WEBINAR ($80)

and then I might want to combine coupons (this could be done simply by adding extra coupons):
a student attending online: STUDENTWEBINAR ($50)
etc.

or by entering more than one coupon:
STUDENT
WEBINAR
new price calculation: $50

and then I offer quantity discounts
2 ordered together 10%
3-5 ordered together 20%
6 or more 30%

Discounting is very important and there are several principles for bulk discounting or upselling that should be incorporated in the purchase form if required.

Otherwise, the membership system is yet another "amateur" product that doesn't understand commercial or ecommerce situations.

Having these options and being able to code them simply will make this a much more professional and useful product.