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	$144.51	11.446%	$161.0506	$161.05	$161.05	$161.10
Purchase #2	$159.76	7.782%	$172.1925	$172.19	$172.20	$172.20
Purchase #3	$11.80	5.853%	$12.4907	$12.49	$12.50	$12.50
Purchase #4	$247.51	7.610%	$266.3455	$266.35	$266.35	$266.30
Purchase #5	$210.84	6.660%	$224.8819	$224.88	$224.90	$224.90
Purchase #6	$153.84	5.386%	$162.1258	$162.13	$162.15	$162.10
Purchase #7	$89.88	10.297%	$99.1349	$99.13	$99.15	$99.10
7 purchase totals =	$1,018.14		$1,098.2219	$1,098.22	$1,098.30	$1,098.20