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	$107.66	11.327%	$119.8546	$119.85	$119.85	$119.90
Purchase #2	$101.28	11.111%	$112.5332	$112.53	$112.55	$112.50
Purchase #3	$118.25	8.123%	$127.8554	$127.86	$127.85	$127.90
Purchase #4	$209.49	4.741%	$219.4219	$219.42	$219.40	$219.40
Purchase #5	$173.75	3.616%	$180.0328	$180.03	$180.05	$180.00
Purchase #6	$58.86	6.340%	$62.5917	$62.59	$62.60	$62.60
Purchase #7	$229.69	3.706%	$238.2023	$238.20	$238.20	$238.20
7 purchase totals =	$998.98		$1,060.4919	$1,060.48	$1,060.50	$1,060.50