Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$145.85	11.383%	$162.4521	$162.45	$162.45	$162.50
Purchase #2	$214.63	10.443%	$237.0438	$237.04	$237.05	$237.00
Purchase #3	$6.98	5.724%	$7.3795	$7.38	$7.40	$7.40
Purchase #4	$45.33	11.207%	$50.4101	$50.41	$50.40	$50.40
Purchase #5	$209.33	10.444%	$231.1924	$231.19	$231.20	$231.20
Purchase #6	$228.86	10.155%	$252.1007	$252.10	$252.10	$252.10
Purchase #7	$225.65	13.325%	$255.7179	$255.72	$255.70	$255.70
7 purchase totals =	$1,076.63		$1,196.2965	$1,196.29	$1,196.30	$1,196.30