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	$184.45	5.748%	$195.0522	$195.05	$195.05	$195.10
Purchase #2	$226.78	8.458%	$245.9611	$245.96	$245.95	$246.00
Purchase #3	$57.64	7.661%	$62.0558	$62.06	$62.05	$62.10
Purchase #4	$69.94	3.552%	$72.4243	$72.42	$72.40	$72.40
Purchase #5	$244.92	4.492%	$255.9218	$255.92	$255.90	$255.90
Purchase #6	$107.97	3.676%	$111.939	$111.94	$111.95	$111.90
Purchase #7	$85.71	10.379%	$94.6058	$94.61	$94.60	$94.60
7 purchase totals =	$977.41		$1,037.9600	$1,037.96	$1,037.90	$1,038.00