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	$178.43	7.696%	$192.162	$192.16	$192.15	$192.20
Purchase #2	$208.67	6.201%	$221.6096	$221.61	$221.60	$221.60
Purchase #3	$250.69	4.673%	$262.4047	$262.40	$262.40	$262.40
Purchase #4	$78.54	6.758%	$83.8477	$83.85	$83.85	$83.80
Purchase #5	$33.44	4.439%	$34.9244	$34.92	$34.90	$34.90
Purchase #6	$43.57	11.319%	$48.5017	$48.50	$48.50	$48.50
Purchase #7	$229.55	6.535%	$244.5511	$244.55	$244.55	$244.60
7 purchase totals =	$1,022.89		$1,088.0012	$1,087.99	$1,087.95	$1,088.00