Grocery stores are masters at finding ways to get you to spend just a little bit more before you leave. One of the most common tactics is the checkout upsell, where a cashier or a machine asks if you want to donate or buy an extra item. While it might seem like a small amount, these requests are carefully designed to break down your resistance. Every extra dollar you agree to spend at the register adds up over the course of a full year. Here is the checkout upsell you should always decline to protect your budget.