For product pricing. Round to 'attractive' prices which don't scare off customers, e.g. 10.99, 10.50, 10.00, 9.95, etc.

round_to_attractive_price.py

from decimal import Decimal


def round_to_attractive_price(
    value, attractive_after_decimals=(0, 50, 95, 99)
):
    rounded = round(Decimal(value), 2)
    before_decimal, after_decimal = str(rounded).split('.')
    after_decimal = min(
        attractive_after_decimals,
        key=lambda num: abs(num - int(after_decimal))
    )
    return Decimal(f'{before_decimal}.{after_decimal}')


"""
from decimal import Decimal

import pytest

from round_price import round_to_attractive_price


@pytest.mark.parametrize('value, expected_value', [
    (Decimal('10.22'), Decimal('10.00')),
    (Decimal('10.43'), Decimal('10.50')),
    (Decimal('1.88'), Decimal('1.95')),
    (Decimal('1.98'), Decimal('1.99')),
    (Decimal('0.15'), Decimal('0.00')),
    (Decimal('0.96'), Decimal('0.95')),
])
def test_round_to_attractive_price(value, expected_value):
    assert round_to_attractive_price(value=value) == expected_value
"""