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	$203.75	5.333%	$214.616	$214.62	$214.60	$214.60
Purchase #2	$184.92	7.522%	$198.8297	$198.83	$198.85	$198.80
Purchase #3	$238.59	8.512%	$258.8988	$258.90	$258.90	$258.90
Purchase #4	$10.31	7.405%	$11.0735	$11.07	$11.05	$11.10
Purchase #5	$32.45	10.357%	$35.8108	$35.81	$35.80	$35.80
Purchase #6	$104.38	3.597%	$108.1345	$108.13	$108.15	$108.10
Purchase #7	$231.42	11.718%	$258.5378	$258.54	$258.55	$258.50
7 purchase totals =	$1,005.82		$1,085.9011	$1,085.90	$1,085.90	$1,085.80