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	$197.48	8.536%	$214.3369	$214.34	$214.35	$214.30
Purchase #2	$136.27	13.390%	$154.5166	$154.52	$154.50	$154.50
Purchase #3	$163.34	7.853%	$176.1671	$176.17	$176.15	$176.20
Purchase #4	$135.98	11.686%	$151.8706	$151.87	$151.85	$151.90
Purchase #5	$183.34	11.515%	$204.4516	$204.45	$204.45	$204.50
Purchase #6	$185.65	4.433%	$193.8799	$193.88	$193.90	$193.90
Purchase #7	$57.90	3.482%	$59.9161	$59.92	$59.90	$59.90
7 purchase totals =	$1,059.96		$1,155.1388	$1,155.15	$1,155.10	$1,155.20