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	$182.34	7.151%	$195.3791	$195.38	$195.40	$195.40
Purchase #2	$167.61	9.478%	$183.4961	$183.50	$183.50	$183.50
Purchase #3	$155.49	5.772%	$164.4649	$164.46	$164.45	$164.50
Purchase #4	$45.40	13.337%	$51.455	$51.46	$51.45	$51.50
Purchase #5	$112.78	9.804%	$123.837	$123.84	$123.85	$123.80
Purchase #6	$201.99	4.157%	$210.3867	$210.39	$210.40	$210.40
Purchase #7	$116.30	10.434%	$128.4347	$128.43	$128.45	$128.40
7 purchase totals =	$981.91		$1,057.4535	$1,057.46	$1,057.50	$1,057.50