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	$90.70	3.661%	$94.0205	$94.02	$94.00	$94.00
Purchase #2	$45.62	9.829%	$50.104	$50.10	$50.10	$50.10
Purchase #3	$66.39	7.116%	$71.1143	$71.11	$71.10	$71.10
Purchase #4	$25.91	5.692%	$27.3848	$27.38	$27.40	$27.40
Purchase #5	$18.82	8.492%	$20.4182	$20.42	$20.40	$20.40
Purchase #6	$19.61	4.366%	$20.4662	$20.47	$20.45	$20.50
Purchase #7	$100.37	11.631%	$112.044	$112.04	$112.05	$112.00
7 purchase totals =	$367.42		$395.5520	$395.54	$395.50	$395.50