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	$63.46	13.165%	$71.8145	$71.81	$71.80	$71.80
Purchase #2	$64.48	10.846%	$71.4735	$71.47	$71.45	$71.50
Purchase #3	$170.61	11.147%	$189.6279	$189.63	$189.65	$189.60
Purchase #4	$182.68	9.677%	$200.3579	$200.36	$200.35	$200.40
Purchase #5	$59.34	12.175%	$66.5646	$66.56	$66.55	$66.60
Purchase #6	$12.42	12.754%	$14.004	$14.00	$14.00	$14.00
Purchase #7	$71.58	13.256%	$81.0686	$81.07	$81.05	$81.10
7 purchase totals =	$624.57		$694.9110	$694.90	$694.85	$695.00