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	$73.78	5.279%	$77.6748	$77.67	$77.65	$77.70
Purchase #2	$173.94	6.500%	$185.2461	$185.25	$185.25	$185.20
Purchase #3	$107.27	3.743%	$111.2851	$111.29	$111.30	$111.30
Purchase #4	$162.30	6.569%	$172.9615	$172.96	$172.95	$173.00
Purchase #5	$87.70	13.433%	$99.4807	$99.48	$99.50	$99.50
Purchase #6	$148.62	6.256%	$157.9177	$157.92	$157.90	$157.90
Purchase #7	$205.69	3.343%	$212.5662	$212.57	$212.55	$212.60
7 purchase totals =	$959.30		$1,017.1321	$1,017.14	$1,017.10	$1,017.20