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	$90.62	5.490%	$95.595	$95.60	$95.60	$95.60
Purchase #2	$58.54	11.829%	$65.4647	$65.46	$65.45	$65.50
Purchase #3	$203.77	7.103%	$218.2438	$218.24	$218.25	$218.20
Purchase #4	$136.95	9.859%	$150.4519	$150.45	$150.45	$150.50
Purchase #5	$176.44	4.748%	$184.8174	$184.82	$184.80	$184.80
Purchase #6	$241.87	10.449%	$267.143	$267.14	$267.15	$267.10
Purchase #7	$33.52	11.860%	$37.4955	$37.50	$37.50	$37.50
7 purchase totals =	$941.71		$1,019.2113	$1,019.21	$1,019.20	$1,019.20