I never do that when I've bought chocolate. I must not be autistic. In fact whenever I buy several items at once I usually only have a vague idea how much it's going to cost, especially with the half-dozen or so taxes on it. When I was a teenager I was really afraid of the thought of having to buy groceries and other items on my own because I was so bad at math and the taxes, which they don't bother telling you about because they want you to forget the items cost more than it says on the price tag.
And when I do buy chocolate, or anything else, it's like I'm playing a game of chess. I'll stand there, trying to decide which of the 50 or so different brands, flavors, consistencies and qualities I want, and of course there are all the different prices. Then someone will ask me to move so they can get their shopping cart past me, disrupting my thoughts. I let them pass saying sorry about three times, then go back to deciding. Finally I reach out to pick a box. But then I'll see something else I like that's on sale. The another shopper needs to get their cart past me. Say sorry two or three times while I let them pass. Then try to remember where the brand with the cheaper price that I like is. Reach out and take the box and put it in my cart. Then I can't get my cart down the aisle because three people are standing there with their carts yakking to each other and blocking my way. Decide to go the opposite direction instead of asking them to move. Accidentally bump into another shopper. Say sorry about six times while adding in a lower voice "sorry for existing".
No wonder the life is sucked out of me by the time I get home.