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	$46.93	3.405%	$48.528	$48.53	$48.55	$48.50
Purchase #2	$33.76	5.109%	$35.4848	$35.48	$35.50	$35.50
Purchase #3	$6.76	12.800%	$7.6253	$7.63	$7.65	$7.60
Purchase #4	$243.45	7.447%	$261.5797	$261.58	$261.60	$261.60
Purchase #5	$173.95	3.343%	$179.7651	$179.77	$179.75	$179.80
Purchase #6	$146.92	13.476%	$166.7189	$166.72	$166.70	$166.70
Purchase #7	$155.25	7.252%	$166.5087	$166.51	$166.50	$166.50
7 purchase totals =	$807.02		$866.2105	$866.22	$866.25	$866.20