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	$190.70	7.679%	$205.3439	$205.34	$205.35	$205.30
Purchase #2	$179.45	6.386%	$190.9097	$190.91	$190.90	$190.90
Purchase #3	$216.85	11.352%	$241.4668	$241.47	$241.45	$241.50
Purchase #4	$153.72	12.450%	$172.8581	$172.86	$172.85	$172.90
Purchase #5	$88.98	8.647%	$96.6741	$96.67	$96.65	$96.70
Purchase #6	$105.43	4.484%	$110.1575	$110.16	$110.15	$110.20
Purchase #7	$133.81	6.407%	$142.3832	$142.38	$142.40	$142.40
7 purchase totals =	$1,068.94		$1,159.7933	$1,159.79	$1,159.75	$1,159.90