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	$95.41	12.151%	$107.0033	$107.00	$107.00	$107.00
Purchase #2	$20.68	4.359%	$21.5814	$21.58	$21.60	$21.60
Purchase #3	$146.90	5.800%	$155.4202	$155.42	$155.40	$155.40
Purchase #4	$77.71	7.368%	$83.4357	$83.44	$83.45	$83.40
Purchase #5	$126.33	4.181%	$131.6119	$131.61	$131.60	$131.60
Purchase #6	$214.97	11.776%	$240.2849	$240.28	$240.30	$240.30
Purchase #7	$138.82	12.762%	$156.5362	$156.54	$156.55	$156.50
7 purchase totals =	$820.82		$895.8736	$895.87	$895.90	$895.80