Checkout allows buyers to request information from you regarding the total amount. If the buyer requests information, you will receive an email from eBay. Click on the "Send payment information" link in the email to update the payment information for the buyer. You can also find this link in My eBay.
On the "Update payment information" page, you can update the Postage & Packaging and Postage insurance fees for your item, but only after the listing ends.*
Updated information will be reflected in Checkout and on the Checkout Summary page, but will not appear on the Listing page.
* Please note that the buyer reserves his/her right to accept the amounts you submit if the amounts change without probable cause.