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	$178.60	3.548%	$184.9367	$184.94	$184.95	$184.90
Purchase #2	$184.43	3.535%	$190.9496	$190.95	$190.95	$190.90
Purchase #3	$160.92	10.808%	$178.3122	$178.31	$178.30	$178.30
Purchase #4	$138.99	5.401%	$146.4968	$146.50	$146.50	$146.50
Purchase #5	$129.28	5.570%	$136.4809	$136.48	$136.50	$136.50
Purchase #6	$180.99	11.108%	$201.0944	$201.09	$201.10	$201.10
Purchase #7	$139.72	13.163%	$158.1113	$158.11	$158.10	$158.10
7 purchase totals =	$1,112.93		$1,196.3819	$1,196.38	$1,196.40	$1,196.30