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	$232.31	7.558%	$249.868	$249.87	$249.85	$249.90
Purchase #2	$18.54	7.580%	$19.9453	$19.95	$19.95	$19.90
Purchase #3	$99.62	4.327%	$103.9306	$103.93	$103.95	$103.90
Purchase #4	$47.60	13.645%	$54.095	$54.10	$54.10	$54.10
Purchase #5	$172.94	7.232%	$185.447	$185.45	$185.45	$185.40
Purchase #6	$34.78	8.835%	$37.8528	$37.85	$37.85	$37.90
Purchase #7	$153.92	3.645%	$159.5304	$159.53	$159.55	$159.50
7 purchase totals =	$759.71		$810.6691	$810.68	$810.70	$810.60