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	$212.53	9.697%	$233.139	$233.14	$233.15	$233.10
Purchase #2	$114.70	7.626%	$123.447	$123.45	$123.45	$123.40
Purchase #3	$69.60	5.746%	$73.5992	$73.60	$73.60	$73.60
Purchase #4	$67.99	11.868%	$76.0591	$76.06	$76.05	$76.10
Purchase #5	$200.62	3.610%	$207.8624	$207.86	$207.85	$207.90
Purchase #6	$77.66	11.131%	$86.3043	$86.30	$86.30	$86.30
Purchase #7	$209.36	4.362%	$218.4923	$218.49	$218.50	$218.50
7 purchase totals =	$952.46		$1,018.9033	$1,018.90	$1,018.90	$1,018.90