Sweets-for-coins supermarket unfair

I am writing as a citizen with a lean purse. On Sunday, September 5 at about noon, I bought items at Uchumi Supermarkets Jogoo Road branch.
I went to pay, then the cashier decides I should have sweets instead of my loose change.

This had happened to the customer ahead of me and my son on the queue.
I told the cashier, I didn’t want sweets. He ignored me. After minutes he threw three sweets on the counter next to me and continued.

At the till, there was not a single shilling. Why did I smell a rat and think that this was intentional?

Why is Uchumi forcing us to buy sweets?

EVELYN OPIYO, Nairobi