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	$71.35	3.535%	$73.8722	$73.87	$73.85	$73.90
Purchase #2	$200.98	8.243%	$217.5468	$217.55	$217.55	$217.50
Purchase #3	$208.84	7.658%	$224.833	$224.83	$224.85	$224.80
Purchase #4	$116.83	8.831%	$127.1473	$127.15	$127.15	$127.10
Purchase #5	$90.47	11.577%	$100.9437	$100.94	$100.95	$100.90
Purchase #6	$238.58	11.708%	$266.5129	$266.51	$266.50	$266.50
Purchase #7	$22.76	5.102%	$23.9212	$23.92	$23.90	$23.90
7 purchase totals =	$949.81		$1,034.7771	$1,034.77	$1,034.75	$1,034.60