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	$164.67	5.451%	$173.6462	$173.65	$173.65	$173.60
Purchase #2	$13.43	3.203%	$13.8602	$13.86	$13.85	$13.90
Purchase #3	$31.80	13.647%	$36.1397	$36.14	$36.15	$36.10
Purchase #4	$187.59	4.685%	$196.3786	$196.38	$196.40	$196.40
Purchase #5	$59.60	7.506%	$64.0736	$64.07	$64.05	$64.10
Purchase #6	$143.70	10.852%	$159.2943	$159.29	$159.30	$159.30
Purchase #7	$39.38	3.111%	$40.6051	$40.61	$40.60	$40.60
7 purchase totals =	$640.17		$683.9977	$684.00	$684.00	$684.00