I've had numerous run-ins with businesses that try to impose a minimum amount when you use a debit card. This violates the merchant agreement with the credit card company!
Here's the guidance the businesses get from MasterCard/Visa:
Visa® & MasterCard® Rules and Regulations
As a merchant accepting MasterCard® and Visa®, there are basic card acceptance rules that you must follow. By adhering to these rules, you can increase customer satisfaction and ensure that you do not run into compliance issues, which may put your continued ability to accept credit cards at risk. The following are some of the rules outlined in the Visa and MasterCard manuals:
Card Logos & Acceptance: You must display the appropriate card logos for any card types that you accept and advise your customers of their payment options. You must honor all categories of cards (credit, debit, rewards etc.) within each card type that you accept.
Dollar Minimums and Maximums: You may not impose a minimum or maximum amount for any transactions. If you do not accept a customer charge, which is below a certain amount that you specify, the customer can notify Visa and/or MasterCard, who will take the appropriate steps to see that you understand and adhere to the card acceptance rules and regulations.
I've filed more complaints than you would believe, and every time I've given the merchant the chance to avoid it, they stick to their guns. I'm not sure they even know the rule; some do and just don't care because they know WE don't know. The next time you see that sign that says, "MINIMUM $10.00 charge on credit/debit cards," tell them it's AGAINST the rule. If they give you a hard time, complain to the credit card company.
On another note, saw this when visiting Pennsylvania, and thought it was great:
The Amish Challenge:
If you admire our faith, strengthen yours.
If you admire our sense of commitment, deepen yours.
If you admire our community spirit, build your own.
If you admire our simple life, cut back.
If you admire deep character and enduring values, live them yourself.
See ya next time.