Startup Idea : Charity for things you purchase online

What if you could contribute to Charity for every dollar you spent for your luxury? For example, every accommodation you book, spa treatments, expensive restaurants, flights, even expensive clothes and bags, you automatically give 1 - 5% of your purchase to charity. Some people feel guilty to spend a lot of money for their luxury knowing that there's still hunger in a lot of countries, but if they know that they could contribute to end the world hunger while they're having a good time? they would be very happy.