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	$184.56	8.714%	$200.6426	$200.64	$200.65	$200.60
Purchase #2	$160.77	12.353%	$180.6299	$180.63	$180.65	$180.60
Purchase #3	$239.72	9.535%	$262.5773	$262.58	$262.60	$262.60
Purchase #4	$147.70	5.754%	$156.1987	$156.20	$156.20	$156.20
Purchase #5	$119.39	3.447%	$123.5054	$123.51	$123.50	$123.50
Purchase #6	$26.90	10.586%	$29.7476	$29.75	$29.75	$29.70
Purchase #7	$96.94	11.578%	$108.1637	$108.16	$108.15	$108.20
7 purchase totals =	$975.98		$1,061.4652	$1,061.47	$1,061.50	$1,061.40