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	$164.38	11.124%	$182.6656	$182.67	$182.65	$182.70
Purchase #2	$84.27	7.853%	$90.8877	$90.89	$90.90	$90.90
Purchase #3	$129.55	11.526%	$144.4819	$144.48	$144.50	$144.50
Purchase #4	$121.38	8.609%	$131.8296	$131.83	$131.85	$131.80
Purchase #5	$65.58	4.840%	$68.7541	$68.75	$68.75	$68.80
Purchase #6	$216.59	7.139%	$232.0524	$232.05	$232.05	$232.10
Purchase #7	$202.72	5.661%	$214.196	$214.20	$214.20	$214.20
7 purchase totals =	$984.47		$1,064.8673	$1,064.87	$1,064.90	$1,065.00