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	$55.57	10.171%	$61.222	$61.22	$61.20	$61.20
Purchase #2	$140.39	9.130%	$153.2076	$153.21	$153.20	$153.20
Purchase #3	$12.73	13.430%	$14.4396	$14.44	$14.45	$14.40
Purchase #4	$145.90	5.198%	$153.4839	$153.48	$153.50	$153.50
Purchase #5	$98.61	6.597%	$105.1153	$105.12	$105.10	$105.10
Purchase #6	$90.63	3.830%	$94.1011	$94.10	$94.10	$94.10
Purchase #7	$139.41	8.668%	$151.4941	$151.49	$151.50	$151.50
7 purchase totals =	$683.24		$733.0636	$733.06	$733.05	$733.00