Add cart surcharges, handling fees, and extra charges to Shopify checkout. Use for processing fees, expedited shipping, rush orders, shipping insurance, gift wrap service, tip collection, donation box, environmental fees, fragile item handling, oversized product charges, and custom service fees. Customers choose to add fees with an opt-in toggle. Keep 100% of revenue—zero commission or revenue sharing. Compatible with slide cart, cart drawer, cart page, and all Online Store 2.0 themes.