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	$197.54	7.746%	$212.8414	$212.84	$212.85	$212.80
Purchase #2	$114.56	10.241%	$126.2921	$126.29	$126.30	$126.30
Purchase #3	$164.78	4.471%	$172.1473	$172.15	$172.15	$172.10
Purchase #4	$78.90	5.575%	$83.2987	$83.30	$83.30	$83.30
Purchase #5	$103.45	4.465%	$108.069	$108.07	$108.05	$108.10
Purchase #6	$176.84	9.255%	$193.2065	$193.21	$193.20	$193.20
Purchase #7	$241.39	6.298%	$256.5927	$256.59	$256.60	$256.60
7 purchase totals =	$1,077.46		$1,152.4477	$1,152.45	$1,152.45	$1,152.40