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	$178.46	10.579%	$197.3393	$197.34	$197.35	$197.30
Purchase #2	$167.82	11.704%	$187.4617	$187.46	$187.45	$187.50
Purchase #3	$179.69	4.303%	$187.4221	$187.42	$187.40	$187.40
Purchase #4	$227.60	6.367%	$242.0913	$242.09	$242.10	$242.10
Purchase #5	$102.95	9.708%	$112.9444	$112.94	$112.95	$112.90
Purchase #6	$39.47	6.680%	$42.1066	$42.11	$42.10	$42.10
Purchase #7	$85.73	11.750%	$95.8033	$95.80	$95.80	$95.80
7 purchase totals =	$981.72		$1,065.1687	$1,065.16	$1,065.15	$1,065.10