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	$196.79	7.749%	$212.0393	$212.04	$212.05	$212.00
Purchase #2	$67.78	5.407%	$71.4449	$71.44	$71.45	$71.40
Purchase #3	$217.46	10.571%	$240.4477	$240.45	$240.45	$240.40
Purchase #4	$5.87	10.570%	$6.4905	$6.49	$6.50	$6.50
Purchase #5	$232.59	6.272%	$247.178	$247.18	$247.20	$247.20
Purchase #6	$145.59	7.314%	$156.2385	$156.24	$156.25	$156.20
Purchase #7	$118.95	7.471%	$127.8368	$127.84	$127.85	$127.80
7 purchase totals =	$985.03		$1,061.6757	$1,061.68	$1,061.75	$1,061.50