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	$76.54	11.491%	$85.3352	$85.34	$85.35	$85.30
Purchase #2	$39.97	4.355%	$41.7107	$41.71	$41.70	$41.70
Purchase #3	$67.55	13.279%	$76.52	$76.52	$76.50	$76.50
Purchase #4	$90.27	5.700%	$95.4154	$95.42	$95.40	$95.40
Purchase #5	$12.84	12.228%	$14.4101	$14.41	$14.40	$14.40
Purchase #6	$185.42	5.835%	$196.2393	$196.24	$196.25	$196.20
Purchase #7	$197.38	10.165%	$217.4437	$217.44	$217.45	$217.40
7 purchase totals =	$669.97		$727.0744	$727.08	$727.05	$726.90