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	$145.92	4.220%	$152.0778	$152.08	$152.10	$152.10
Purchase #2	$117.91	11.223%	$131.143	$131.14	$131.15	$131.10
Purchase #3	$226.61	8.174%	$245.1331	$245.13	$245.15	$245.10
Purchase #4	$233.32	7.845%	$251.624	$251.62	$251.60	$251.60
Purchase #5	$47.58	13.283%	$53.9001	$53.90	$53.90	$53.90
Purchase #6	$33.37	13.434%	$37.8529	$37.85	$37.85	$37.90
Purchase #7	$154.48	3.827%	$160.3919	$160.39	$160.40	$160.40
7 purchase totals =	$959.19		$1,032.1228	$1,032.11	$1,032.15	$1,032.10