The Best Puzzles #1 – “The 7-11 Store clerk”

I have collected (and made) a lot of cool maths & logic puzzles over the years.
As too many Facebook maths problems today seem uninspired, I have decided to start posting from my collection.

 

Select the text in yellow line below to see the answer.

$1.20, $1.25, $1.50, and $3.16

 

This particular puzzle is from a great book that I got for free when a local library discarded it.
Teaching Middle School Mathematics [Brumbaugh, Ortiz & Gresham]