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	$208.47	11.457%	$232.3544	$232.35	$232.35	$232.40
Purchase #2	$162.76	8.542%	$176.663	$176.66	$176.65	$176.70
Purchase #3	$199.60	7.565%	$214.6997	$214.70	$214.70	$214.70
Purchase #4	$180.48	8.649%	$196.0897	$196.09	$196.10	$196.10
Purchase #5	$168.59	13.429%	$191.23	$191.23	$191.25	$191.20
Purchase #6	$88.99	7.230%	$95.424	$95.42	$95.40	$95.40
Purchase #7	$52.95	12.274%	$59.4491	$59.45	$59.45	$59.40
7 purchase totals =	$1,061.84		$1,165.9099	$1,165.90	$1,165.90	$1,165.90