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	$192.48	7.475%	$206.8679	$206.87	$206.85	$206.90
Purchase #2	$244.68	7.186%	$262.2627	$262.26	$262.25	$262.30
Purchase #3	$177.63	5.565%	$187.5151	$187.52	$187.50	$187.50
Purchase #4	$194.94	7.446%	$209.4552	$209.46	$209.45	$209.50
Purchase #5	$222.39	11.615%	$248.2206	$248.22	$248.20	$248.20
Purchase #6	$120.35	9.389%	$131.6497	$131.65	$131.65	$131.60
Purchase #7	$229.44	11.327%	$255.4287	$255.43	$255.45	$255.40
7 purchase totals =	$1,381.91		$1,501.3999	$1,501.41	$1,501.35	$1,501.40