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	$209.58	3.602%	$217.1291	$217.13	$217.15	$217.10
Purchase #2	$127.77	10.567%	$141.2715	$141.27	$141.25	$141.30
Purchase #3	$199.90	7.292%	$214.4767	$214.48	$214.50	$214.50
Purchase #4	$92.93	11.513%	$103.629	$103.63	$103.65	$103.60
Purchase #5	$206.69	8.291%	$223.8267	$223.83	$223.85	$223.80
Purchase #6	$169.37	4.846%	$177.5777	$177.58	$177.60	$177.60
Purchase #7	$199.71	11.859%	$223.3936	$223.39	$223.40	$223.40
7 purchase totals =	$1,205.95		$1,301.3043	$1,301.31	$1,301.40	$1,301.30