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	$155.33	11.408%	$173.05	$173.05	$173.05	$173.10
Purchase #2	$132.31	13.823%	$150.5992	$150.60	$150.60	$150.60
Purchase #3	$66.93	7.797%	$72.1485	$72.15	$72.15	$72.10
Purchase #4	$234.40	11.622%	$261.642	$261.64	$261.65	$261.60
Purchase #5	$77.95	10.150%	$85.8619	$85.86	$85.85	$85.90
Purchase #6	$100.73	5.271%	$106.0395	$106.04	$106.05	$106.00
Purchase #7	$194.88	11.863%	$217.9986	$218.00	$218.00	$218.00
7 purchase totals =	$962.53		$1,067.3397	$1,067.34	$1,067.35	$1,067.30