payload() :: %{
  :taxes => [tax()],
  :raw_price => float(),
  :count_of_persons => non_neg_integer(),
  :count_of_rooms => non_neg_integer(),
  :count_of_nights => non_neg_integer(),
  optional(:calculated_taxes) => list(),
  optional(:inclusive) => nil | list(),
  optional(:exclusive) => nil | list(),
  optional(:net_price) => nil | float(),
  optional(:total_price) => nil | float()
}

tax() :: %{
  title: String.t(),
  rate: float(),
  is_inclusive: boolean(),
  logic: :percent,
  taxes: nil | [tax()]
}