I checked out your code and found one important detail. Your code works fine, but the WHILE loop is never ending. You declared the while loop to keep on going while the value is "25 Cents".
The value of keep_going is a string that will never change. The while loop will then never stop executing the codes inside it.
One way of stopping this would be to add a counter and including an AND into your while loop.
Declare a variable as a counter.
ChestCounter = 1
Now in your while loop add an AND function.
while keep_going == '25 Cents' and ChestCounter < 2:
Now in line with your for loop add the ChestCounter and increment it.
ChestCounter += 1
The code will then execute the while loop and the for loop. After the for loop finishes the 5th execution, it will then increment the ChestCounter and stop the code from executing again.