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	$44.80	4.873%	$46.9831	$46.98	$47.00	$47.00
Purchase #2	$127.94	11.395%	$142.5188	$142.52	$142.50	$142.50
Purchase #3	$214.33	6.622%	$228.5229	$228.52	$228.50	$228.50
Purchase #4	$172.27	8.738%	$187.323	$187.32	$187.30	$187.30
Purchase #5	$154.66	13.744%	$175.9165	$175.92	$175.90	$175.90
Purchase #6	$183.95	3.577%	$190.5299	$190.53	$190.55	$190.50
Purchase #7	$132.36	9.472%	$144.8971	$144.90	$144.90	$144.90
7 purchase totals =	$1,030.31		$1,116.6913	$1,116.69	$1,116.65	$1,116.60