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	$162.29	12.384%	$182.388	$182.39	$182.40	$182.40
Purchase #2	$7.27	5.626%	$7.679	$7.68	$7.70	$7.70
Purchase #3	$222.30	7.315%	$238.5612	$238.56	$238.55	$238.60
Purchase #4	$117.61	11.467%	$131.0963	$131.10	$131.10	$131.10
Purchase #5	$108.62	3.649%	$112.5835	$112.58	$112.60	$112.60
Purchase #6	$45.91	9.270%	$50.1659	$50.17	$50.15	$50.20
Purchase #7	$199.45	11.352%	$222.0916	$222.09	$222.10	$222.10
7 purchase totals =	$863.45		$944.5655	$944.57	$944.60	$944.70