def append_overhead_costs(costs, new_id, overhead_percentage=0.15):
    """
    Adds 15% overhead costs to the list of costs.

    Usage::

        from rapid_prototyping.context.utils import append_overhead_costs
        costs = [
            ....
        ]
        costs = append_overhead_costs(costs, MAIN_ID + get_counter(counter)[0])

    :param costs: Your final list of costs.
    :param new_id: The id that this new item should get.

    """
    total_time = 0
    for item in costs:
        total_time += item['time']
    costs.append({'id': new_id, 'task': 'Overhead, Bufixes & Iterations',
        'time': total_time * overhead_percentage})
    return costs
