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	$197.95	9.370%	$216.4979	$216.50	$216.50	$216.50
Purchase #2	$45.47	6.156%	$48.2691	$48.27	$48.25	$48.30
Purchase #3	$59.97	13.213%	$67.8938	$67.89	$67.90	$67.90
Purchase #4	$234.56	8.763%	$255.1145	$255.11	$255.10	$255.10
Purchase #5	$231.93	8.383%	$251.3727	$251.37	$251.35	$251.40
Purchase #6	$174.70	9.178%	$190.734	$190.73	$190.75	$190.70
Purchase #7	$13.90	9.137%	$15.17	$15.17	$15.15	$15.20
7 purchase totals =	$958.48		$1,045.0520	$1,045.04	$1,045.00	$1,045.10