At this time, we aren't offering the option to run multiple simultaneous campaigns.
Here is a workaround: for example, you can apply the Donate for Discount campaign for certain items, offering 20% off in exchange for a $10 donation. And for a separate set of items you apply the % of Sales campaign, where you donate a % of proceeds from each sale of those items. However, each campaign can only correspond with a specific donation amount - in other words, you can't do different two Donate for Discount campaigns at once at this time.
Please contact firstname.lastname@example.org with any questions.