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	$102.26	12.321%	$114.8595	$114.86	$114.85	$114.90
Purchase #2	$19.94	7.683%	$21.472	$21.47	$21.45	$21.50
Purchase #3	$60.34	12.222%	$67.7148	$67.71	$67.70	$67.70
Purchase #4	$241.40	7.382%	$259.2201	$259.22	$259.20	$259.20
Purchase #5	$181.96	7.424%	$195.4687	$195.47	$195.45	$195.50
Purchase #6	$220.39	8.188%	$238.4355	$238.44	$238.45	$238.40
Purchase #7	$147.96	7.175%	$158.5761	$158.58	$158.60	$158.60
7 purchase totals =	$974.25		$1,055.7467	$1,055.75	$1,055.70	$1,055.80