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	$102.62	8.445%	$111.2863	$111.29	$111.30	$111.30
Purchase #2	$193.66	12.441%	$217.7532	$217.75	$217.75	$217.80
Purchase #3	$96.38	10.488%	$106.4883	$106.49	$106.50	$106.50
Purchase #4	$39.88	3.600%	$41.3157	$41.32	$41.30	$41.30
Purchase #5	$229.97	4.549%	$240.4313	$240.43	$240.45	$240.40
Purchase #6	$185.91	5.475%	$196.0886	$196.09	$196.10	$196.10
Purchase #7	$118.83	3.306%	$122.7585	$122.76	$122.75	$122.80
7 purchase totals =	$967.25		$1,036.1219	$1,036.13	$1,036.15	$1,036.20