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	$222.88	8.551%	$241.9385	$241.94	$241.95	$241.90
Purchase #2	$88.74	4.680%	$92.893	$92.89	$92.90	$92.90
Purchase #3	$103.35	4.540%	$108.0421	$108.04	$108.05	$108.00
Purchase #4	$59.60	13.213%	$67.4749	$67.47	$67.45	$67.50
Purchase #5	$51.92	13.736%	$59.0517	$59.05	$59.05	$59.10
Purchase #6	$243.92	7.769%	$262.8701	$262.87	$262.85	$262.90
Purchase #7	$210.72	7.142%	$225.7696	$225.77	$225.75	$225.80
7 purchase totals =	$981.13		$1,058.0399	$1,058.03	$1,058.00	$1,058.10