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	$89.69	6.264%	$95.3082	$95.31	$95.30	$95.30
Purchase #2	$180.83	5.146%	$190.1355	$190.14	$190.15	$190.10
Purchase #3	$10.82	6.464%	$11.5194	$11.52	$11.50	$11.50
Purchase #4	$152.35	13.333%	$172.6628	$172.66	$172.65	$172.70
Purchase #5	$234.65	4.795%	$245.9015	$245.90	$245.90	$245.90
Purchase #6	$223.60	4.626%	$233.9437	$233.94	$233.95	$233.90
Purchase #7	$199.58	13.537%	$226.5971	$226.60	$226.60	$226.60
7 purchase totals =	$1,091.52		$1,176.0682	$1,176.07	$1,176.05	$1,176.00