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	$62.93	4.147%	$65.5397	$65.54	$65.55	$65.50
Purchase #2	$186.56	5.436%	$196.7014	$196.70	$196.70	$196.70
Purchase #3	$172.84	3.142%	$178.2706	$178.27	$178.25	$178.30
Purchase #4	$14.73	8.116%	$15.9255	$15.93	$15.95	$15.90
Purchase #5	$240.89	6.759%	$257.1718	$257.17	$257.15	$257.20
Purchase #6	$114.45	3.514%	$118.4718	$118.47	$118.45	$118.50
Purchase #7	$54.50	3.252%	$56.2723	$56.27	$56.25	$56.30
7 purchase totals =	$846.90		$888.3531	$888.35	$888.30	$888.40