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	$174.45	12.466%	$196.1969	$196.20	$196.20	$196.20
Purchase #2	$152.36	13.338%	$172.6818	$172.68	$172.70	$172.70
Purchase #3	$145.39	3.315%	$150.2097	$150.21	$150.20	$150.20
Purchase #4	$24.95	4.501%	$26.073	$26.07	$26.05	$26.10
Purchase #5	$221.35	4.733%	$231.8265	$231.83	$231.85	$231.80
Purchase #6	$161.78	12.796%	$182.4814	$182.48	$182.50	$182.50
Purchase #7	$150.51	11.693%	$168.1091	$168.11	$168.10	$168.10
7 purchase totals =	$1,030.79		$1,127.5784	$1,127.58	$1,127.60	$1,127.60