Especially if it is at a threshold amount, there even a small hike will scare away customers. While not reasonable, it is a psychological effect. Take the jump from 5€ to 6€. I witnessed the same on myself with a normal dish of fried rice from a take away place. 4,5€ is cheap, 5€ expected, 5,5€ makes no difference, but 6€??

No matter how stupid, the jump by 50cent to 6€ gets me every time. It makes no sense, but I start to calculate what I could get instead on the cheap end. Breakfast to go is the same with 3€ to 3,5€ to 4€. I mean could get a portion of fried rice for 4€! Same goes for pizza or any number of take away items.

It doesnt help that most shop owners arent stupid and optimized for those thresholds.