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	$197.69	7.690%	$212.8924	$212.89	$212.90	$212.90
Purchase #2	$121.40	4.692%	$127.0961	$127.10	$127.10	$127.10
Purchase #3	$244.31	12.225%	$274.1769	$274.18	$274.20	$274.20
Purchase #4	$118.49	7.776%	$127.7038	$127.70	$127.70	$127.70
Purchase #5	$89.74	8.357%	$97.2396	$97.24	$97.25	$97.20
Purchase #6	$245.69	3.235%	$253.6381	$253.64	$253.65	$253.60
Purchase #7	$16.83	11.749%	$18.8074	$18.81	$18.80	$18.80
7 purchase totals =	$1,034.15		$1,111.5543	$1,111.56	$1,111.60	$1,111.50