Factors can change between the time you place an order and the time of credit card charge authorization, which could affect the calculation of sales taxes.
Authorization is the process by which MasterCard validates the card, and Settlement fees are charged to issuers for the exchange of funds between issuers and acquirers.
However, after the cap on swipe fees, Visa will try to maintain the current level of authorization and settlement fee make up for the lost revenues on debit card fees.
And banks typically require adult authorization for children to set up a bank account with a linked debit card, which can act as a credit card for the purposes of online accounts.
The Fed believes that banks should only recover certain items through interchange fees including the variable costs that are directly attributable to the authorization, clearance, and settlement of the transaction (including the transaction fees paid to the card networks).