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	$183.63	3.815%	$190.6355	$190.64	$190.65	$190.60
Purchase #2	$10.76	6.501%	$11.4595	$11.46	$11.45	$11.50
Purchase #3	$158.35	11.690%	$176.8611	$176.86	$176.85	$176.90
Purchase #4	$32.67	6.612%	$34.8301	$34.83	$34.85	$34.80
Purchase #5	$118.51	4.285%	$123.5882	$123.59	$123.60	$123.60
Purchase #6	$245.80	9.522%	$269.2051	$269.21	$269.20	$269.20
Purchase #7	$176.30	7.697%	$189.8698	$189.87	$189.85	$189.90
7 purchase totals =	$926.02		$996.4493	$996.46	$996.45	$996.50