SAPICA is an IC card which can be used for transportation in Sapporo. It also can be used for shopping in some stores.
I use it whenever I take a bus, subway or streetcar because I can receive 10% discounts on it. For example, if I pay 200 yen as fare of subway by SAPICA, I will gain 20 SAPICA points, 10% of its fare. After saving SAPICA points more than fare you pay, the fare will be paid by SAPICA points instead of money.
SAPICA points can also be gained in some convenience stores in the city when you pay by SAPICA.