I only accept to have those sugary sweet if they search very well for my change without success

That's the way to go. I also do this just failed to deliver most of my thoughts properly. I didn't count cultural differences and forgotten people have different economic systems. Brazil is cool is this regard. If it's 99 they will only charge 95. They round off to 5, not the nearest but what benefits the customer most. I learned a lot from this heated blog. It's good that I wrote and people bombarded me with different opinions and especially brazil ones.