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	$233.59	4.301%	$243.6367	$243.64	$243.65	$243.60
Purchase #2	$186.83	3.794%	$193.9183	$193.92	$193.90	$193.90
Purchase #3	$186.42	7.373%	$200.1647	$200.16	$200.15	$200.20
Purchase #4	$92.29	12.468%	$103.7967	$103.80	$103.80	$103.80
Purchase #5	$238.70	8.293%	$258.4954	$258.50	$258.50	$258.50
Purchase #6	$33.72	8.485%	$36.5811	$36.58	$36.60	$36.60
Purchase #7	$155.61	11.120%	$172.9138	$172.91	$172.90	$172.90
7 purchase totals =	$1,127.16		$1,209.5067	$1,209.51	$1,209.50	$1,209.50