Does this give me a different answer than a generic fee calculator?
A generic calculator returns a clean per-charge number. An annual software plan does not behave that way. Support cost spreads across twelve months, a refund mid-year claws back the full amount, and a launch discount changes the base Stripe charges against. The preset above stacks those in the order they hit an annual sale so the figure you see is what survives the year, not what the headline price looked like on day one.