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	$83.64	10.416%	$92.3519	$92.35	$92.35	$92.40
Purchase #2	$170.61	3.413%	$176.4329	$176.43	$176.45	$176.40
Purchase #3	$208.83	11.466%	$232.7744	$232.77	$232.75	$232.80
Purchase #4	$106.85	4.595%	$111.7598	$111.76	$111.75	$111.80
Purchase #5	$47.85	12.449%	$53.8068	$53.81	$53.80	$53.80
Purchase #6	$223.53	5.354%	$235.4978	$235.50	$235.50	$235.50
Purchase #7	$153.51	5.841%	$162.4765	$162.48	$162.50	$162.50
7 purchase totals =	$994.82		$1,065.1001	$1,065.10	$1,065.10	$1,065.20