Yes, you can set up to 10% discounts for the preset shopping cart in Price Settings of your affiliate account (you can use the option on making 5 sales through the affiliate link or preset shopping cart).
Additionally you can create and give customers up to 10% promo codes from the affiliate area Promo Codes Generator (this option can be used regardless the amount of sales made but it should be noted that the generated promo codes are only active for template purchases made through your affiliate link (if you set the this promo code discount for the affiliate link) or the chosen preset shopping cart.
Either of the options gives a way to set a discount with the affiliate commission amount, i.e. if your commission is 30% and someone purchases a template at 10% through your preset shopping cart or uses your 10% promo code the commission amount you get is only the remaining 20%.
If you have more questions feel free to contact our affiliate support by submitting a ticket request.