How much does Stripe charge for each transaction?

Stripe takes a simple approach. They charge a flat rate of 2.9% + 30¢ per successful charge.

Stripe does not disclose any special high volume rates, but you can contact the company, (sales@stripe.com) if you cross over the $80,000 dollar volume per month threshold. You can view the Stripe pricing policy here: Stripe – Simple Pricing.