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	$125.27	3.811%	$130.044	$130.04	$130.05	$130.00
Purchase #2	$93.27	7.514%	$100.2783	$100.28	$100.30	$100.30
Purchase #3	$85.77	7.790%	$92.4515	$92.45	$92.45	$92.50
Purchase #4	$153.55	12.604%	$172.9034	$172.90	$172.90	$172.90
Purchase #5	$229.44	11.361%	$255.5067	$255.51	$255.50	$255.50
Purchase #6	$240.60	10.748%	$266.4597	$266.46	$266.45	$266.50
Purchase #7	$13.39	4.862%	$14.041	$14.04	$14.05	$14.00
7 purchase totals =	$941.29		$1,031.6846	$1,031.68	$1,031.70	$1,031.70