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	$146.82	9.619%	$160.9426	$160.94	$160.95	$160.90
Purchase #2	$14.58	5.253%	$15.3459	$15.35	$15.35	$15.30
Purchase #3	$53.36	11.579%	$59.5386	$59.54	$59.55	$59.50
Purchase #4	$78.35	12.582%	$88.208	$88.21	$88.20	$88.20
Purchase #5	$151.78	6.399%	$161.4924	$161.49	$161.50	$161.50
Purchase #6	$69.87	11.821%	$78.1293	$78.13	$78.15	$78.10
Purchase #7	$175.66	9.170%	$191.768	$191.77	$191.75	$191.80
7 purchase totals =	$690.42		$755.4248	$755.43	$755.45	$755.30