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	$182.45	4.480%	$190.6238	$190.62	$190.60	$190.60
Purchase #2	$9.82	10.196%	$10.8212	$10.82	$10.80	$10.80
Purchase #3	$99.83	8.489%	$108.3046	$108.30	$108.30	$108.30
Purchase #4	$73.98	7.314%	$79.3909	$79.39	$79.40	$79.40
Purchase #5	$78.49	3.820%	$81.4883	$81.49	$81.50	$81.50
Purchase #6	$190.46	13.624%	$216.4083	$216.41	$216.40	$216.40
Purchase #7	$82.87	6.554%	$88.3013	$88.30	$88.30	$88.30
7 purchase totals =	$717.90		$775.3384	$775.33	$775.30	$775.30