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	$190.74	3.519%	$197.4521	$197.45	$197.45	$197.50
Purchase #2	$179.41	4.260%	$187.0529	$187.05	$187.05	$187.10
Purchase #3	$38.60	5.761%	$40.8237	$40.82	$40.80	$40.80
Purchase #4	$199.90	8.318%	$216.5277	$216.53	$216.55	$216.50
Purchase #5	$214.35	4.248%	$223.4556	$223.46	$223.45	$223.50
Purchase #6	$62.37	7.316%	$66.933	$66.93	$66.95	$66.90
Purchase #7	$197.67	11.561%	$220.5226	$220.52	$220.50	$220.50
7 purchase totals =	$1,083.04		$1,152.7676	$1,152.76	$1,152.75	$1,152.80