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	$85.91	3.247%	$88.6995	$88.70	$88.70	$88.70
Purchase #2	$10.69	4.278%	$11.1473	$11.15	$11.15	$11.10
Purchase #3	$99.37	5.211%	$104.5482	$104.55	$104.55	$104.50
Purchase #4	$177.77	10.489%	$196.4163	$196.42	$196.40	$196.40
Purchase #5	$235.81	9.131%	$257.3418	$257.34	$257.35	$257.30
Purchase #6	$32.96	6.570%	$35.1255	$35.13	$35.15	$35.10
Purchase #7	$100.45	13.211%	$113.7204	$113.72	$113.70	$113.70
7 purchase totals =	$742.96		$806.9990	$807.01	$807.00	$806.80