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	$53.86	10.246%	$59.3785	$59.38	$59.40	$59.40
Purchase #2	$86.87	10.591%	$96.0704	$96.07	$96.05	$96.10
Purchase #3	$14.31	9.371%	$15.651	$15.65	$15.65	$15.70
Purchase #4	$88.88	3.850%	$92.3019	$92.30	$92.30	$92.30
Purchase #5	$32.51	6.192%	$34.523	$34.52	$34.50	$34.50
Purchase #6	$152.88	4.261%	$159.3942	$159.39	$159.40	$159.40
Purchase #7	$12.33	12.466%	$13.8671	$13.87	$13.85	$13.90
7 purchase totals =	$441.64		$471.1861	$471.18	$471.15	$471.30