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	$233.52	4.546%	$244.1358	$244.14	$244.15	$244.10
Purchase #2	$60.91	5.806%	$64.4464	$64.45	$64.45	$64.40
Purchase #3	$215.41	8.703%	$234.1571	$234.16	$234.15	$234.20
Purchase #4	$50.52	11.859%	$56.5112	$56.51	$56.50	$56.50
Purchase #5	$12.59	11.793%	$14.0747	$14.07	$14.05	$14.10
Purchase #6	$189.69	5.733%	$200.5649	$200.56	$200.55	$200.60
Purchase #7	$215.32	4.519%	$225.0503	$225.05	$225.05	$225.10
7 purchase totals =	$977.96		$1,038.9404	$1,038.94	$1,038.90	$1,039.00