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	$196.31	9.235%	$214.4392	$214.44	$214.45	$214.40
Purchase #2	$160.58	5.201%	$168.9318	$168.93	$168.95	$168.90
Purchase #3	$18.27	3.678%	$18.942	$18.94	$18.95	$18.90
Purchase #4	$194.59	11.201%	$216.386	$216.39	$216.40	$216.40
Purchase #5	$80.84	13.338%	$91.6224	$91.62	$91.60	$91.60
Purchase #6	$111.91	6.168%	$118.8126	$118.81	$118.80	$118.80
Purchase #7	$212.41	9.307%	$232.179	$232.18	$232.20	$232.20
7 purchase totals =	$974.91		$1,061.3130	$1,061.31	$1,061.35	$1,061.20