To figure out how much to charge a field trip attendee, so that they cover any PayPal fees that are incurred, use the following formula.
y = amount you must pay vendor
x = amount you must charge attendee to recoup both the amount paid to vendor and PayPal fees
(y + .3)/.971 = x
For example, if I am running an event that has an admission fee of $8.25 (I must pay the vendor $8.25 per person attending), this is how the formula works:
(8.25 + .3) / .971 = x
8.55 / .971 = x
x = $8.81 (rounded up to the nearest penny)
If I charge each attendee $8.55, I will bring in enough cash to pay both the vendor and to cover my PayPal fees without losing any money.
Those who purchase multiple tickets in a single purchase will be paying 30¢ more per additional ticket than will actually be charged by PayPal. There isn’t a simple way to account for this within the event handler. People can decide individually whether the offered price is acceptable to them or not.
This is the formula that applies to my account. PayPal charges me 30¢ per transaction plus 2.9% of the transaction cost. Yours may differ and you’ll need to check with PayPal for specifics to see if you need to adjust the formula accordingly.