Is a gift presented by commercial stores in Germany to customers, in the form of a 2 Euro check after collecting 200 points for purchases, halal or haram? If it is haram, what should be done to atone for the sin for someone who has received these checks multiple times?

The amounts that stores give to those who buy a certain quantity of goods are price reductions, and there is no harm in them as long as participation is free. This type of reduction is permissible unless it leads to something forbidden, such as deceiving buyers or harming other sellers. The accountable person must not undertake an action before discerning its ruling.