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	$202.81	11.217%	$225.5592	$225.56	$225.55	$225.60
Purchase #2	$203.81	6.693%	$217.451	$217.45	$217.45	$217.50
Purchase #3	$53.25	6.294%	$56.6016	$56.60	$56.60	$56.60
Purchase #4	$33.82	11.574%	$37.7343	$37.73	$37.75	$37.70
Purchase #5	$216.86	3.630%	$224.732	$224.73	$224.75	$224.70
Purchase #6	$47.44	13.189%	$53.6969	$53.70	$53.70	$53.70
Purchase #7	$203.40	6.226%	$216.0637	$216.06	$216.05	$216.10
7 purchase totals =	$961.39		$1,031.8387	$1,031.83	$1,031.85	$1,031.90