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	$212.55	10.193%	$234.2152	$234.22	$234.20	$234.20
Purchase #2	$197.52	5.356%	$208.0992	$208.10	$208.10	$208.10
Purchase #3	$59.85	9.612%	$65.6028	$65.60	$65.60	$65.60
Purchase #4	$172.85	3.172%	$178.3328	$178.33	$178.35	$178.30
Purchase #5	$241.55	9.204%	$263.7823	$263.78	$263.80	$263.80
Purchase #6	$166.30	10.212%	$183.2826	$183.28	$183.30	$183.30
Purchase #7	$98.53	13.162%	$111.4985	$111.50	$111.50	$111.50
7 purchase totals =	$1,149.15		$1,244.8134	$1,244.81	$1,244.85	$1,244.80