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	$226.64	3.512%	$234.5996	$234.60	$234.60	$234.60
Purchase #2	$38.44	13.143%	$43.4922	$43.49	$43.50	$43.50
Purchase #3	$224.52	13.245%	$254.2577	$254.26	$254.25	$254.30
Purchase #4	$249.70	9.311%	$272.9496	$272.95	$272.95	$272.90
Purchase #5	$35.59	7.250%	$38.1703	$38.17	$38.15	$38.20
Purchase #6	$152.94	6.475%	$162.8429	$162.84	$162.85	$162.80
Purchase #7	$10.89	12.249%	$12.2239	$12.22	$12.20	$12.20
7 purchase totals =	$938.72		$1,018.5362	$1,018.53	$1,018.50	$1,018.50