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	$40.73	13.511%	$46.233	$46.23	$46.25	$46.20
Purchase #2	$60.43	5.741%	$63.8993	$63.90	$63.90	$63.90
Purchase #3	$222.72	8.585%	$241.8405	$241.84	$241.85	$241.80
Purchase #4	$119.26	5.208%	$125.4711	$125.47	$125.45	$125.50
Purchase #5	$62.88	5.499%	$66.3378	$66.34	$66.35	$66.30
Purchase #6	$245.61	4.259%	$256.0705	$256.07	$256.05	$256.10
Purchase #7	$198.85	8.196%	$215.1477	$215.15	$215.15	$215.10
7 purchase totals =	$950.48		$1,014.9999	$1,015.00	$1,015.00	$1,014.90