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	$12.64	10.443%	$13.96	$13.96	$13.95	$14.00
Purchase #2	$87.31	6.345%	$92.8498	$92.85	$92.85	$92.80
Purchase #3	$148.80	4.586%	$155.624	$155.62	$155.60	$155.60
Purchase #4	$49.91	5.236%	$52.5233	$52.52	$52.50	$52.50
Purchase #5	$68.76	12.199%	$77.148	$77.15	$77.15	$77.10
Purchase #6	$224.71	4.613%	$235.0759	$235.08	$235.10	$235.10
Purchase #7	$112.47	13.660%	$127.8334	$127.83	$127.85	$127.80
7 purchase totals =	$704.60		$755.0144	$755.01	$755.00	$754.90