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	$158.29	11.178%	$175.9837	$175.98	$176.00	$176.00
Purchase #2	$248.44	10.603%	$274.7821	$274.78	$274.80	$274.80
Purchase #3	$35.51	10.638%	$39.2876	$39.29	$39.30	$39.30
Purchase #4	$196.40	4.619%	$205.4717	$205.47	$205.45	$205.50
Purchase #5	$49.29	13.363%	$55.8766	$55.88	$55.90	$55.90
Purchase #6	$249.75	5.235%	$262.8244	$262.82	$262.80	$262.80
Purchase #7	$237.39	7.510%	$255.218	$255.22	$255.20	$255.20
7 purchase totals =	$1,175.07		$1,269.4441	$1,269.44	$1,269.45	$1,269.50