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	$128.82	3.583%	$133.4356	$133.44	$133.45	$133.40
Purchase #2	$14.86	6.873%	$15.8813	$15.88	$15.90	$15.90
Purchase #3	$228.64	4.482%	$238.8876	$238.89	$238.90	$238.90
Purchase #4	$115.52	7.429%	$124.102	$124.10	$124.10	$124.10
Purchase #5	$221.79	8.831%	$241.3763	$241.38	$241.40	$241.40
Purchase #6	$211.86	4.865%	$222.167	$222.17	$222.15	$222.20
Purchase #7	$101.80	9.161%	$111.1259	$111.13	$111.15	$111.10
7 purchase totals =	$1,023.29		$1,086.9757	$1,086.99	$1,087.05	$1,087.00