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	$69.59	5.444%	$73.3785	$73.38	$73.40	$73.40
Purchase #2	$80.97	5.619%	$85.5197	$85.52	$85.50	$85.50
Purchase #3	$212.40	5.677%	$224.4579	$224.46	$224.45	$224.50
Purchase #4	$6.51	9.155%	$7.106	$7.11	$7.10	$7.10
Purchase #5	$71.60	8.685%	$77.8185	$77.82	$77.80	$77.80
Purchase #6	$232.25	13.384%	$263.3343	$263.33	$263.35	$263.30
Purchase #7	$19.78	5.310%	$20.8303	$20.83	$20.85	$20.80
7 purchase totals =	$693.10		$752.4452	$752.45	$752.45	$752.40