Is this a bug of discount?

[George-Liu]

Hi,

I encountered a strange thing，I set a free shipping threshold of $35.9 and a 15% abandonment coupon code,The price of one of my product is $41.9.

If a customer buys 1 product and applies a 15% off discount, shouldn’t it be $41.9-(15%×$41.9)=$35.62 plus shipping costs?

However, the actual customer only paid $35.82. I have tested the discount on the website. In the above case, I need to pay $35.82 plus shipping cost.

I don't konw why.Is this a bug of discount?