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	$219.28	4.554%	$229.266	$229.27	$229.25	$229.30
Purchase #2	$212.50	6.167%	$225.6049	$225.60	$225.60	$225.60
Purchase #3	$193.29	11.513%	$215.5435	$215.54	$215.55	$215.50
Purchase #4	$200.47	8.672%	$217.8548	$217.85	$217.85	$217.90
Purchase #5	$58.25	7.846%	$62.8203	$62.82	$62.80	$62.80
Purchase #6	$95.47	9.105%	$104.1625	$104.16	$104.15	$104.20
Purchase #7	$227.43	10.761%	$251.9037	$251.90	$251.90	$251.90
7 purchase totals =	$1,206.69		$1,307.1557	$1,307.14	$1,307.10	$1,307.20