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	$59.56	3.461%	$61.6214	$61.62	$61.60	$61.60
Purchase #2	$81.91	3.719%	$84.9562	$84.96	$84.95	$85.00
Purchase #3	$70.27	9.118%	$76.6772	$76.68	$76.70	$76.70
Purchase #4	$80.88	12.359%	$90.876	$90.88	$90.90	$90.90
Purchase #5	$51.89	9.511%	$56.8253	$56.83	$56.85	$56.80
Purchase #6	$47.86	9.219%	$52.2722	$52.27	$52.25	$52.30
Purchase #7	$149.58	6.513%	$159.3221	$159.32	$159.30	$159.30
7 purchase totals =	$541.95		$582.5504	$582.56	$582.55	$582.60