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	$100.99	10.203%	$111.294	$111.29	$111.30	$111.30
Purchase #2	$104.55	6.206%	$111.0384	$111.04	$111.05	$111.00
Purchase #3	$197.26	11.470%	$219.8857	$219.89	$219.90	$219.90
Purchase #4	$230.45	11.338%	$256.5784	$256.58	$256.60	$256.60
Purchase #5	$83.77	6.551%	$89.2578	$89.26	$89.25	$89.30
Purchase #6	$152.85	6.543%	$162.851	$162.85	$162.85	$162.90
Purchase #7	$191.28	6.601%	$203.9064	$203.91	$203.90	$203.90
7 purchase totals =	$1,061.15		$1,154.8117	$1,154.82	$1,154.85	$1,154.90