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	$103.61	13.742%	$117.8481	$117.85	$117.85	$117.80
Purchase #2	$142.78	8.771%	$155.3032	$155.30	$155.30	$155.30
Purchase #3	$183.78	8.158%	$198.7728	$198.77	$198.75	$198.80
Purchase #4	$179.80	5.577%	$189.8274	$189.83	$189.85	$189.80
Purchase #5	$126.59	4.327%	$132.0675	$132.07	$132.05	$132.10
Purchase #6	$148.52	13.763%	$168.9608	$168.96	$168.95	$169.00
Purchase #7	$57.70	3.800%	$59.8926	$59.89	$59.90	$59.90
7 purchase totals =	$942.78		$1,022.6724	$1,022.67	$1,022.65	$1,022.70