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	$216.75	3.375%	$224.0653	$224.07	$224.05	$224.10
Purchase #2	$74.42	11.226%	$82.7744	$82.77	$82.75	$82.80
Purchase #3	$199.31	10.424%	$220.0861	$220.09	$220.10	$220.10
Purchase #4	$211.92	8.784%	$230.5351	$230.54	$230.55	$230.50
Purchase #5	$49.37	4.432%	$51.5581	$51.56	$51.55	$51.60
Purchase #6	$103.59	7.441%	$111.2981	$111.30	$111.30	$111.30
Purchase #7	$161.76	7.314%	$173.5911	$173.59	$173.60	$173.60
7 purchase totals =	$1,017.12		$1,093.9082	$1,093.92	$1,093.90	$1,094.00