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	$12.92	13.665%	$14.6855	$14.69	$14.70	$14.70
Purchase #2	$45.93	13.871%	$52.301	$52.30	$52.30	$52.30
Purchase #3	$41.51	13.507%	$47.1168	$47.12	$47.10	$47.10
Purchase #4	$104.45	9.696%	$114.5775	$114.58	$114.60	$114.60
Purchase #5	$239.58	10.707%	$265.2318	$265.23	$265.25	$265.20
Purchase #6	$43.36	10.841%	$48.0607	$48.06	$48.05	$48.10
Purchase #7	$110.77	11.427%	$123.4277	$123.43	$123.45	$123.40
7 purchase totals =	$598.52		$665.4010	$665.41	$665.45	$665.40