LaterPay is set up so that payment processing fees are constrained.
Bank processing fees are fixed: if each of your small purchases were processed separately, the relatively high cost of processing each of them separately would not allow Merchants to offer low prices. By combining all of your purchases from different Merchants where you agreed to “Pay Later,” LaterPay can submit one payment and get charged one fee. LaterPay handles dividing that one payment between the Merchants that you bought content from.
LaterPay uses a cutoff value of $5 because that is high enough to make revenue for each Merchant, but low enough to be reached by the majority of LaterPay users relatively quickly.