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	$98.47	6.694%	$105.0616	$105.06	$105.05	$105.10
Purchase #2	$149.28	10.665%	$165.2007	$165.20	$165.20	$165.20
Purchase #3	$248.66	3.283%	$256.8235	$256.82	$256.80	$256.80
Purchase #4	$101.38	13.769%	$115.339	$115.34	$115.35	$115.30
Purchase #5	$222.77	7.489%	$239.4532	$239.45	$239.45	$239.50
Purchase #6	$57.44	3.407%	$59.397	$59.40	$59.40	$59.40
Purchase #7	$223.26	4.422%	$233.1326	$233.13	$233.15	$233.10
7 purchase totals =	$1,101.26		$1,174.4076	$1,174.40	$1,174.40	$1,174.40