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	$172.42	7.647%	$185.605	$185.61	$185.60	$185.60
Purchase #2	$200.65	4.580%	$209.8398	$209.84	$209.85	$209.80
Purchase #3	$19.71	5.715%	$20.8364	$20.84	$20.85	$20.80
Purchase #4	$243.47	6.648%	$259.6559	$259.66	$259.65	$259.70
Purchase #5	$215.78	12.148%	$241.993	$241.99	$242.00	$242.00
Purchase #6	$236.84	3.321%	$244.7055	$244.71	$244.70	$244.70
Purchase #7	$40.87	11.322%	$45.4973	$45.50	$45.50	$45.50
7 purchase totals =	$1,129.74		$1,208.1329	$1,208.15	$1,208.15	$1,208.10