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	$126.83	13.831%	$144.3719	$144.37	$144.35	$144.40
Purchase #2	$214.77	3.398%	$222.0679	$222.07	$222.05	$222.10
Purchase #3	$193.90	6.335%	$206.1836	$206.18	$206.20	$206.20
Purchase #4	$66.65	7.796%	$71.846	$71.85	$71.85	$71.80
Purchase #5	$51.45	10.595%	$56.9011	$56.90	$56.90	$56.90
Purchase #6	$81.42	13.406%	$92.3352	$92.34	$92.35	$92.30
Purchase #7	$202.59	10.146%	$223.1448	$223.14	$223.15	$223.10
7 purchase totals =	$937.61		$1,016.8505	$1,016.85	$1,016.85	$1,016.80