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	$232.53	11.223%	$258.6268	$258.63	$258.65	$258.60
Purchase #2	$64.48	3.201%	$66.544	$66.54	$66.55	$66.50
Purchase #3	$48.65	11.313%	$54.1538	$54.15	$54.15	$54.20
Purchase #4	$70.42	3.499%	$72.884	$72.88	$72.90	$72.90
Purchase #5	$210.95	4.716%	$220.8984	$220.90	$220.90	$220.90
Purchase #6	$175.35	12.226%	$196.7883	$196.79	$196.80	$196.80
Purchase #7	$173.64	13.839%	$197.67	$197.67	$197.65	$197.70
7 purchase totals =	$976.02		$1,067.5653	$1,067.56	$1,067.60	$1,067.60