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	$107.25	11.818%	$119.9248	$119.92	$119.90	$119.90
Purchase #2	$13.72	6.789%	$14.6515	$14.65	$14.65	$14.70
Purchase #3	$31.79	8.628%	$34.5328	$34.53	$34.55	$34.50
Purchase #4	$65.56	11.217%	$72.9139	$72.91	$72.90	$72.90
Purchase #5	$95.90	4.717%	$100.4236	$100.42	$100.40	$100.40
Purchase #6	$183.98	11.693%	$205.4928	$205.49	$205.50	$205.50
Purchase #7	$174.51	5.870%	$184.7537	$184.75	$184.75	$184.80
7 purchase totals =	$672.71		$732.6931	$732.67	$732.65	$732.70