The PHPBuilder.com site has a tutorial posted helping you integrate Stripe into your PHP application as a payment gateway service.

Stripe is a payment gateway that is becoming increasingly popular in the Web industry. It offers payment processing services, which can be easily integrated into your Web application using the Stripe API.

Although it is not free (2.9% + 30 cents per transaction), Stripe saves time and reduces cost in many ways: seamless integration and good documentation reduces the amount of time and development hours needed, while it offers complete control over sensitive data which saves hundreds of thousands of dollars that would otherwise be spent on ensuring PCI compliance.

They then show how to set up and use the PHP Stripe API package to create a simple checkout form to accept credit card information and use the stripe.js handling to send it directly to Stripe. Once the service receives it, it then makes a call back to your callback endpoint to create a token value for the transaction and customer. This callback then uses the API to make the actual charge using the token for the payment method and the customer information.