Aggregation of validated transactions for settlement

A merchant system comprising:

• a merchant central computer;
• and
• a plurality of merchant terminals communicatively coupled to the merchant central computer, wherein each of the merchant terminals transmits transaction data of at least one offline transaction conducted at the merchant terminal to the central computer, the offline transaction conducted at the merchant terminal permitting a consumer to receive and use a good or service from the merchant prior to requesting online payment authorization from an issuer of a portable payment device used for the offline transaction,
• wherein the merchant central computer aggregates the transaction data received from the plurality of merchant terminals into an aggregation set of offline transactions and sends the aggregation set of offline transactions in a batch to a payment processing system to request online payment authorization from one or more issuers when the aggregation set of offline transactions satisfy a predetermined transaction aggregation criteria, and
• wherein the aggregation set of offline transactions includes offline transactions that were conducted using a plurality of portable payment devices, and at least one of the offline transactions in the aggregation set of offline transactions has a transaction amount that is unknown at the time of the offline transaction, and the merchant central computer determines the transaction amount from the transaction data in the aggregation set of offline transactions.