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	$177.60	10.456%	$196.1699	$196.17	$196.15	$196.20
Purchase #2	$208.66	7.243%	$223.7732	$223.77	$223.75	$223.80
Purchase #3	$156.88	12.355%	$176.2625	$176.26	$176.25	$176.30
Purchase #4	$47.81	13.814%	$54.4145	$54.41	$54.40	$54.40
Purchase #5	$108.37	5.250%	$114.0594	$114.06	$114.05	$114.10
Purchase #6	$153.51	13.171%	$173.7288	$173.73	$173.75	$173.70
Purchase #7	$47.62	11.558%	$53.1239	$53.12	$53.10	$53.10
7 purchase totals =	$900.45		$991.5322	$991.52	$991.45	$991.60