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	$145.59	5.665%	$153.8377	$153.84	$153.85	$153.80
Purchase #2	$163.67	8.471%	$177.5345	$177.53	$177.55	$177.50
Purchase #3	$24.29	3.490%	$25.1377	$25.14	$25.15	$25.10
Purchase #4	$181.36	8.328%	$196.4637	$196.46	$196.45	$196.50
Purchase #5	$220.99	11.209%	$245.7608	$245.76	$245.75	$245.80
Purchase #6	$233.63	9.161%	$255.0328	$255.03	$255.05	$255.00
Purchase #7	$48.72	6.156%	$51.7192	$51.72	$51.70	$51.70
7 purchase totals =	$1,018.25		$1,105.4864	$1,105.48	$1,105.50	$1,105.40