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	$209.78	4.769%	$219.7844	$219.78	$219.80	$219.80
Purchase #2	$58.28	9.301%	$63.7006	$63.70	$63.70	$63.70
Purchase #3	$136.93	10.461%	$151.2542	$151.25	$151.25	$151.30
Purchase #4	$175.98	9.391%	$192.5063	$192.51	$192.50	$192.50
Purchase #5	$33.50	10.768%	$37.1073	$37.11	$37.10	$37.10
Purchase #6	$161.32	11.859%	$180.4509	$180.45	$180.45	$180.50
Purchase #7	$164.98	4.749%	$172.8149	$172.81	$172.80	$172.80
7 purchase totals =	$940.77		$1,017.6186	$1,017.61	$1,017.60	$1,017.70