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	$59.55	4.307%	$62.1148	$62.11	$62.10	$62.10
Purchase #2	$20.57	8.489%	$22.3162	$22.32	$22.30	$22.30
Purchase #3	$8.57	3.232%	$8.847	$8.85	$8.85	$8.80
Purchase #4	$126.99	13.203%	$143.7565	$143.76	$143.75	$143.80
Purchase #5	$175.96	11.532%	$196.2517	$196.25	$196.25	$196.30
Purchase #6	$52.44	13.637%	$59.5912	$59.59	$59.60	$59.60
Purchase #7	$162.99	10.737%	$180.4902	$180.49	$180.50	$180.50
7 purchase totals =	$607.07		$673.3676	$673.37	$673.35	$673.40