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	$226.61	3.493%	$234.5255	$234.53	$234.55	$234.50
Purchase #2	$24.27	13.508%	$27.5484	$27.55	$27.55	$27.50
Purchase #3	$227.42	8.108%	$245.8592	$245.86	$245.85	$245.90
Purchase #4	$246.67	13.746%	$280.5773	$280.58	$280.60	$280.60
Purchase #5	$87.37	10.781%	$96.7894	$96.79	$96.80	$96.80
Purchase #6	$72.88	5.395%	$76.8119	$76.81	$76.80	$76.80
Purchase #7	$180.77	8.831%	$196.7338	$196.73	$196.75	$196.70
7 purchase totals =	$1,065.99		$1,158.8455	$1,158.85	$1,158.90	$1,158.80