jmrker's script does not work - it returns NaN because
<div>$1.00 <button value="1.00" onclick="bump(this.value)"> rake leaves/bag </button> </div>
returns "rake leaves", not 1.00
I think you need to specify<!DOCTYPE html>
or use <input type = "button"
But I cannot get the local storage to work - in any case it will not work in IE when run locally (not on line).
All the code given in this post has been tested and is intended to address the question asked.
Unless stated otherwise it is not just a demonstration.