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	$216.74	5.203%	$228.017	$228.02	$228.00	$228.00
Purchase #2	$156.58	12.802%	$176.6254	$176.63	$176.65	$176.60
Purchase #3	$13.46	8.442%	$14.5963	$14.60	$14.60	$14.60
Purchase #4	$100.86	4.142%	$105.0376	$105.04	$105.05	$105.00
Purchase #5	$107.50	3.724%	$111.5033	$111.50	$111.50	$111.50
Purchase #6	$31.65	5.446%	$33.3737	$33.37	$33.35	$33.40
Purchase #7	$207.88	4.223%	$216.6588	$216.66	$216.65	$216.70
7 purchase totals =	$834.67		$885.8121	$885.82	$885.80	$885.80