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	$176.57	11.462%	$196.8085	$196.81	$196.80	$196.80
Purchase #2	$182.46	5.547%	$192.5811	$192.58	$192.60	$192.60
Purchase #3	$158.84	13.298%	$179.9625	$179.96	$179.95	$180.00
Purchase #4	$40.74	4.826%	$42.7061	$42.71	$42.70	$42.70
Purchase #5	$158.83	10.846%	$176.0567	$176.06	$176.05	$176.10
Purchase #6	$177.62	3.519%	$183.8704	$183.87	$183.85	$183.90
Purchase #7	$120.59	9.266%	$131.7639	$131.76	$131.75	$131.80
7 purchase totals =	$1,015.65		$1,103.7492	$1,103.75	$1,103.70	$1,103.90