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	$137.28	11.359%	$152.8736	$152.87	$152.85	$152.90
Purchase #2	$176.72	10.621%	$195.4894	$195.49	$195.50	$195.50
Purchase #3	$139.39	10.103%	$153.4726	$153.47	$153.45	$153.50
Purchase #4	$198.83	5.224%	$209.2169	$209.22	$209.20	$209.20
Purchase #5	$48.42	6.128%	$51.3872	$51.39	$51.40	$51.40
Purchase #6	$218.89	5.557%	$231.0537	$231.05	$231.05	$231.10
Purchase #7	$25.94	13.544%	$29.4533	$29.45	$29.45	$29.50
7 purchase totals =	$945.47		$1,022.9467	$1,022.94	$1,022.90	$1,023.10