This isn’t a perfect solution, and not automatic, but what about adding it as the final line item, with a price value of 0.029, and the quantity of your full fee?
EG:
Transaction Amount: 100
Item: PayPal Service Fee
Price: 0.029
Quantity: 100
Total: 2.91
That then gets added to the final total.
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This reply was modified 4 years, 9 months ago by seleis. Reason: Added example