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	$218.31	5.749%	$230.8606	$230.86	$230.85	$230.90
Purchase #2	$82.66	4.666%	$86.5169	$86.52	$86.50	$86.50
Purchase #3	$98.45	3.170%	$101.5709	$101.57	$101.55	$101.60
Purchase #4	$136.78	13.406%	$155.1167	$155.12	$155.10	$155.10
Purchase #5	$226.87	6.785%	$242.2631	$242.26	$242.25	$242.30
Purchase #6	$237.86	6.841%	$254.132	$254.13	$254.15	$254.10
Purchase #7	$145.64	5.110%	$153.0822	$153.08	$153.10	$153.10
7 purchase totals =	$1,146.57		$1,223.5424	$1,223.54	$1,223.50	$1,223.60