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	$200.46	5.561%	$211.6076	$211.61	$211.60	$211.60
Purchase #2	$40.43	11.715%	$45.1664	$45.17	$45.15	$45.20
Purchase #3	$157.83	9.245%	$172.4214	$172.42	$172.40	$172.40
Purchase #4	$18.88	13.401%	$21.4101	$21.41	$21.40	$21.40
Purchase #5	$168.93	6.215%	$179.429	$179.43	$179.45	$179.40
Purchase #6	$135.89	8.197%	$147.0289	$147.03	$147.05	$147.00
Purchase #7	$218.70	13.476%	$248.172	$248.17	$248.15	$248.20
7 purchase totals =	$941.12		$1,025.2354	$1,025.24	$1,025.20	$1,025.20