Tolkein's publisher wishes to implement an online store for the "Lord of the Rings" and "The Hobbit" books. Each book costs $10. However, if 2 titles are purchased, a 5% discount will be received, i.e. purchasing "Fellowship of the Ring" and "Two Towers" will cost $19. If 3 different titles are purchased, a 10% discount will be received. The purchase of all 4 different titles will receive a 20% discount. An additional single title will be full-price. The encoding of an order will be in the form of strings in an array. For example: [“F”, “T”, “R”, “H”, “H”] is the encoding of 2 copies of "The Hobbit" and a single copy of each of the titles in the "Lord of the Rings" trilogy. The expected output is a number. E.g. 42 is the expected output for the example above. The output should be the cheapest total cost. For example - if the book order is ["F", "T", "H", "F", "T", "R"], valid total costs include (3*10 discounted by 10%) + (3*10 discounted by 10%) and (4*10 discounted by 20%) + (2*10 discounted by 5%). The cheapest total cost is 51.

def calculate_total(order):
  # your code here
  # order is a string array listing the titles
  # return the cheapest total cost

calculate_total(["F", "T", "H", "F", "T", "R"])