1. A computer-implemented method comprising: receiving, by one or more processors of a payment system, from a point-of-sale (POS) computing device of a merchant, transaction data for a plurality of financial transactions corresponding to purchases by a plurality of customers of a plurality of first items from an inventory of the merchant, the transaction data including payment data and an indication of the first items and other items purchased for the financial transactions; determining, by the one or more processors, a quantity of the first item for the merchant to purchase to replenish the inventory; determining, by the one or more processors, based at least partially on the transaction data received from the POS computing device, a financing amount for enabling the merchant to purchase at least a portion of the quantity of the first item for replenishing the first item in the inventory; sending, by the one or more processors, a notification to the POS computing device of the merchant that causes a merchant application on the POS computing device to display an inventory interface concurrently with a transaction interface, the inventory interface presenting a message indicating the quantity of the first item for replenishing the inventory and further presenting an offer for the financing amount, wherein the transaction interface on the POS computing device is used to conduct the financial transactions between the merchant and the customers of the merchant; receiving, by the one or more processors, via the inventory interface presented on the POS computing device, an acceptance of the offer for the financing amount from the POS computing device of the merchant; and providing, by the one or more processors, the financing amount to a financial account of the merchant.