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	$93.59	3.547%	$96.9096	$96.91	$96.90	$96.90
Purchase #2	$7.60	13.345%	$8.6142	$8.61	$8.60	$8.60
Purchase #3	$226.77	6.660%	$241.8729	$241.87	$241.85	$241.90
Purchase #4	$242.58	13.203%	$274.6078	$274.61	$274.60	$274.60
Purchase #5	$52.39	4.212%	$54.5967	$54.60	$54.60	$54.60
Purchase #6	$143.37	5.361%	$151.0561	$151.06	$151.05	$151.10
Purchase #7	$57.27	12.816%	$64.6097	$64.61	$64.60	$64.60
7 purchase totals =	$823.57		$892.2670	$892.27	$892.20	$892.30