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	$197.35	11.403%	$219.8538	$219.85	$219.85	$219.90
Purchase #2	$51.55	12.187%	$57.8324	$57.83	$57.85	$57.80
Purchase #3	$38.27	9.561%	$41.929	$41.93	$41.95	$41.90
Purchase #4	$11.94	3.315%	$12.3358	$12.34	$12.35	$12.30
Purchase #5	$50.44	11.771%	$56.3773	$56.38	$56.40	$56.40
Purchase #6	$157.79	5.143%	$165.9051	$165.91	$165.90	$165.90
Purchase #7	$111.86	10.235%	$123.3089	$123.31	$123.30	$123.30
7 purchase totals =	$619.20		$677.5423	$677.55	$677.60	$677.50