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	$117.94	7.726%	$127.052	$127.05	$127.05	$127.10
Purchase #2	$138.99	6.199%	$147.606	$147.61	$147.60	$147.60
Purchase #3	$178.77	5.102%	$187.8908	$187.89	$187.90	$187.90
Purchase #4	$241.72	3.488%	$250.1512	$250.15	$250.15	$250.20
Purchase #5	$221.63	11.748%	$247.6671	$247.67	$247.65	$247.70
Purchase #6	$15.38	4.724%	$16.1066	$16.11	$16.10	$16.10
Purchase #7	$88.58	7.274%	$95.0233	$95.02	$95.00	$95.00
7 purchase totals =	$1,003.01		$1,071.4970	$1,071.50	$1,071.45	$1,071.60