Hi there,
Thanks for joining the Community. QuickBooks is a user-friendly platform that helps you receive payments from your clients with ease. I'll be happy to provide the information you need so you're on the right track.
QuickBooks Online payments charges a service fee of 2.9% $0.25 per transaction per transaction. The taxes are already included in this transaction. I encourage you to learn more about the rates and breakdowns for using QuickBooks Online Payments using this link here.
Let me know if you've also considered the per transaction fee in the calculations. I'll be a message away in case you need anything else.