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	$231.59	13.461%	$262.7643	$262.76	$262.75	$262.80
Purchase #2	$83.62	13.586%	$94.9806	$94.98	$95.00	$95.00
Purchase #3	$235.93	8.412%	$255.7764	$255.78	$255.80	$255.80
Purchase #4	$22.99	11.460%	$25.6247	$25.62	$25.60	$25.60
Purchase #5	$130.92	5.353%	$137.9281	$137.93	$137.95	$137.90
Purchase #6	$85.38	5.834%	$90.3611	$90.36	$90.35	$90.40
Purchase #7	$77.87	7.197%	$83.4743	$83.47	$83.45	$83.50
7 purchase totals =	$868.30		$950.9095	$950.90	$950.90	$951.00