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In the 1970s, Daniel Kahneman and Amos Tversky spun a wheel of fortune in front of their volunteers. It was rigged: it could only land on 10 or 65. Then they asked what percentage of African countries belonged to the UN.
Those who had seen the 10 answered 25% on average. Those who had seen the 65 said 45%. A random number with nothing to do with the question had dragged their answers along like a magnet.
This is the anchoring effect, and shops have mastered it: that "was 99, now 59" isn't there to inform you — it's there to nail the 99 into your head so the 59 feels like a gift.
The unsettling part: knowing the trick doesn't protect you. Anchors work on forewarned experts too. Your brain always negotiates from the first number it sees.