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	$200.52	13.609%	$227.8088	$227.81	$227.80	$227.80
Purchase #2	$100.56	4.622%	$105.2079	$105.21	$105.20	$105.20
Purchase #3	$39.54	8.773%	$43.0088	$43.01	$43.00	$43.00
Purchase #4	$184.77	7.244%	$198.1547	$198.15	$198.15	$198.20
Purchase #5	$176.87	11.184%	$196.6511	$196.65	$196.65	$196.70
Purchase #6	$217.39	6.171%	$230.8051	$230.81	$230.80	$230.80
Purchase #7	$43.72	4.456%	$45.6682	$45.67	$45.65	$45.70
7 purchase totals =	$963.37		$1,047.3046	$1,047.31	$1,047.25	$1,047.40