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	$88.44	4.687%	$92.5852	$92.59	$92.60	$92.60
Purchase #2	$10.55	5.698%	$11.1511	$11.15	$11.15	$11.20
Purchase #3	$153.74	4.545%	$160.7275	$160.73	$160.75	$160.70
Purchase #4	$74.95	10.827%	$83.0648	$83.06	$83.05	$83.10
Purchase #5	$241.89	13.105%	$273.5897	$273.59	$273.60	$273.60
Purchase #6	$32.59	3.465%	$33.7192	$33.72	$33.70	$33.70
Purchase #7	$123.86	11.559%	$138.177	$138.18	$138.20	$138.20
7 purchase totals =	$726.02		$793.0145	$793.02	$793.05	$793.10