It authorizes the transaction and sends bits whizzing back, a 39, 000-kilometer roundtrip journey that involves five stops plus a calculation of how much to charge the merchant in fees and how to divvy up those fees among the banks.

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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.

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"This was clearly with prior calculation and design, " a component of the death penalty aggravated murder charge, Baumoel said.

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