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	$79.39	7.661%	$85.4721	$85.47	$85.45	$85.50
Purchase #2	$87.29	4.177%	$90.9361	$90.94	$90.95	$90.90
Purchase #3	$102.87	8.187%	$111.292	$111.29	$111.30	$111.30
Purchase #4	$50.69	7.675%	$54.5805	$54.58	$54.60	$54.60
Purchase #5	$226.92	3.342%	$234.5037	$234.50	$234.50	$234.50
Purchase #6	$180.34	13.412%	$204.5272	$204.53	$204.55	$204.50
Purchase #7	$214.33	8.247%	$232.0058	$232.01	$232.00	$232.00
7 purchase totals =	$941.83		$1,013.3174	$1,013.32	$1,013.35	$1,013.30