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	$241.47	4.468%	$252.2589	$252.26	$252.25	$252.30
Purchase #2	$95.48	5.194%	$100.4392	$100.44	$100.45	$100.40
Purchase #3	$75.55	13.588%	$85.8157	$85.82	$85.80	$85.80
Purchase #4	$130.65	4.374%	$136.3646	$136.36	$136.35	$136.40
Purchase #5	$242.46	13.715%	$275.7134	$275.71	$275.70	$275.70
Purchase #6	$198.31	9.196%	$216.5466	$216.55	$216.55	$216.50
Purchase #7	$100.71	4.588%	$105.3306	$105.33	$105.35	$105.30
7 purchase totals =	$1,084.63		$1,172.4690	$1,172.47	$1,172.45	$1,172.40