feat(sales): fix bad result in output

subjects/sales/README.md

@@ -91,7 +91,7 @@ And its output:
 ```console
 $ cargo run
 Store { products: [("product A", 1.23), ("product B", 23.1), ("product C", 3.12)] }
-[1.17, 2.98, 22.07]
+[1.17, 2.98, 22.06]
 Cart { items: [("product A", 1.23), ("product B", 23.1), ("product C", 3.12)], receipt: [1.17, 2.98, 22.07] }
 $
 ```