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	$216.52	11.582%	$241.5973	$241.60	$241.60	$241.60
Purchase #2	$192.37	11.569%	$214.6253	$214.63	$214.65	$214.60
Purchase #3	$215.75	6.277%	$229.2926	$229.29	$229.30	$229.30
Purchase #4	$20.58	7.795%	$22.1842	$22.18	$22.20	$22.20
Purchase #5	$190.99	12.418%	$214.7071	$214.71	$214.70	$214.70
Purchase #6	$45.78	8.807%	$49.8118	$49.81	$49.80	$49.80
Purchase #7	$78.74	13.374%	$89.2707	$89.27	$89.25	$89.30
7 purchase totals =	$960.73		$1,061.4890	$1,061.49	$1,061.50	$1,061.50