def calculate_total_bill(subtotal):
    """
    (float) -> float

    subtotal is passed through as an input
    HST_RATE variable in this function is multiplied by inputted variable
    Function returns the resulting variable "total", rounded and formatted to 2 decimal points.
    Variable "total" is then rounded to the nearest 5 cents using the following nickel rounding scheme standard rules in Canada:
    0.01 to 0.02 will round down to 0.00. 0. 03 to 0.04 will round up to 0.05. 0.06 to 0.07 will round down to 0.05.
    0.08 to 0.09 will round up to 0.10


    >>> calculate_total_bill(3.0)
    3.40

    >>> calculate_total_bill(6.67)
    7.55

    >>> calculate_total_bill(2.05)
    2.30

    """
    HST_RATE = 1.13
    total_bill = subtotal *HST_RATE


    return format(round(0.05 * round(float(total_bill)/0.05), 2), '.2f')