You only have to enter information in the boxes that are marked as required. If the box is not marked as required information, you can leave it empty.
Have you checked your confirmation email from Jagex about the purchase? There will also be a confirmation message in the 'Messages' tab of your account here on the website. The only query I would have is if the $1 is a bank fee or PayPal fee to do with the transaction rather than Jagex. The correct price is $5.99 USD.