Custom Fee Structure
There are two ways to update your Custom Fee Structure:
Settings → All Settings → Default Event Fee and Donation (You must have District Official permissions to do this)

This is the default purchase fee structure for the entire box office, and can be changed to absorb fees for your fans. All fees are per-ticket values.
Advanced Event Options → Custom Fee Structure (You must have School Administrator permissions or higher to do this)

Set custom fees for this event to absorb fees for your fans (organization pays any service fees).
Any changes made here will override anything set at the Global level.