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	$206.55	7.565%	$222.1755	$222.18	$222.20	$222.20
Purchase #2	$197.48	12.595%	$222.3526	$222.35	$222.35	$222.40
Purchase #3	$95.98	3.290%	$99.1377	$99.14	$99.15	$99.10
Purchase #4	$247.52	3.699%	$256.6758	$256.68	$256.70	$256.70
Purchase #5	$8.60	11.161%	$9.5598	$9.56	$9.55	$9.60
Purchase #6	$76.64	5.246%	$80.6605	$80.66	$80.65	$80.70
Purchase #7	$127.38	11.601%	$142.1574	$142.16	$142.15	$142.20
7 purchase totals =	$960.15		$1,032.7193	$1,032.73	$1,032.75	$1,032.90