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	$193.46	3.378%	$199.9951	$200.00	$200.00	$200.00
Purchase #2	$122.66	7.286%	$131.597	$131.60	$131.60	$131.60
Purchase #3	$185.58	6.770%	$198.1438	$198.14	$198.15	$198.10
Purchase #4	$71.60	9.221%	$78.2022	$78.20	$78.20	$78.20
Purchase #5	$11.95	3.324%	$12.3472	$12.35	$12.35	$12.30
Purchase #6	$48.92	13.184%	$55.3696	$55.37	$55.35	$55.40
Purchase #7	$90.42	6.695%	$96.4736	$96.47	$96.45	$96.50
7 purchase totals =	$724.59		$772.1285	$772.13	$772.10	$772.10