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	$78.74	8.695%	$85.5864	$85.59	$85.60	$85.60
Purchase #2	$48.46	8.441%	$52.5505	$52.55	$52.55	$52.60
Purchase #3	$183.37	10.458%	$202.5468	$202.55	$202.55	$202.50
Purchase #4	$120.93	11.461%	$134.7898	$134.79	$134.80	$134.80
Purchase #5	$172.86	11.820%	$193.2921	$193.29	$193.30	$193.30
Purchase #6	$244.72	4.414%	$255.5219	$255.52	$255.50	$255.50
Purchase #7	$85.81	8.231%	$92.873	$92.87	$92.85	$92.90
7 purchase totals =	$934.89		$1,017.1605	$1,017.16	$1,017.15	$1,017.20