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	$96.42	13.216%	$109.1629	$109.16	$109.15	$109.20
Purchase #2	$65.53	11.663%	$73.1728	$73.17	$73.15	$73.20
Purchase #3	$197.39	3.487%	$204.273	$204.27	$204.25	$204.30
Purchase #4	$95.64	4.633%	$100.071	$100.07	$100.05	$100.10
Purchase #5	$108.25	13.698%	$123.0781	$123.08	$123.10	$123.10
Purchase #6	$117.75	12.429%	$132.3851	$132.39	$132.40	$132.40
Purchase #7	$231.44	13.357%	$262.3534	$262.35	$262.35	$262.40
7 purchase totals =	$912.42		$1,004.4963	$1,004.49	$1,004.45	$1,004.70