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	$85.96	11.180%	$95.5703	$95.57	$95.55	$95.60
Purchase #2	$117.47	8.493%	$127.4467	$127.45	$127.45	$127.40
Purchase #3	$248.55	5.367%	$261.8897	$261.89	$261.90	$261.90
Purchase #4	$158.54	5.832%	$167.7861	$167.79	$167.80	$167.80
Purchase #5	$21.38	5.551%	$22.5668	$22.57	$22.55	$22.60
Purchase #6	$217.90	13.358%	$247.0071	$247.01	$247.00	$247.00
Purchase #7	$62.39	12.567%	$70.2306	$70.23	$70.25	$70.20
7 purchase totals =	$912.19		$992.4973	$992.51	$992.50	$992.50