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	$216.50	7.703%	$233.177	$233.18	$233.20	$233.20
Purchase #2	$170.77	8.415%	$185.1403	$185.14	$185.15	$185.10
Purchase #3	$146.78	3.549%	$151.9892	$151.99	$152.00	$152.00
Purchase #4	$116.27	8.474%	$126.1227	$126.12	$126.10	$126.10
Purchase #5	$146.94	4.167%	$153.063	$153.06	$153.05	$153.10
Purchase #6	$9.72	3.853%	$10.0945	$10.09	$10.10	$10.10
Purchase #7	$199.76	7.698%	$215.1375	$215.14	$215.15	$215.10
7 purchase totals =	$1,006.74		$1,074.7242	$1,074.72	$1,074.75	$1,074.70