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	$11.73	7.210%	$12.5757	$12.58	$12.60	$12.60
Purchase #2	$43.98	10.329%	$48.5227	$48.52	$48.50	$48.50
Purchase #3	$52.52	12.492%	$59.0808	$59.08	$59.10	$59.10
Purchase #4	$79.81	7.479%	$85.779	$85.78	$85.80	$85.80
Purchase #5	$184.80	11.415%	$205.8949	$205.89	$205.90	$205.90
Purchase #6	$216.30	10.380%	$238.7519	$238.75	$238.75	$238.80
Purchase #7	$227.66	7.430%	$244.5751	$244.58	$244.60	$244.60
7 purchase totals =	$816.80		$895.1801	$895.18	$895.25	$895.30