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	$41.77	3.831%	$43.3702	$43.37	$43.35	$43.40
Purchase #2	$230.62	7.327%	$247.5175	$247.52	$247.50	$247.50
Purchase #3	$211.80	3.255%	$218.6941	$218.69	$218.70	$218.70
Purchase #4	$95.65	4.300%	$99.763	$99.76	$99.75	$99.80
Purchase #5	$247.90	3.631%	$256.9012	$256.90	$256.90	$256.90
Purchase #6	$98.30	6.756%	$104.9411	$104.94	$104.95	$104.90
Purchase #7	$49.83	11.393%	$55.5071	$55.51	$55.50	$55.50
7 purchase totals =	$975.87		$1,026.6942	$1,026.69	$1,026.65	$1,026.70