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	$62.82	13.736%	$71.449	$71.45	$71.45	$71.40
Purchase #2	$233.43	13.747%	$265.5196	$265.52	$265.50	$265.50
Purchase #3	$72.35	5.579%	$76.3864	$76.39	$76.40	$76.40
Purchase #4	$79.33	8.523%	$86.0913	$86.09	$86.10	$86.10
Purchase #5	$197.94	3.860%	$205.5805	$205.58	$205.60	$205.60
Purchase #6	$128.66	13.127%	$145.5492	$145.55	$145.55	$145.50
Purchase #7	$99.95	12.239%	$112.1829	$112.18	$112.20	$112.20
7 purchase totals =	$874.48		$962.7589	$962.76	$962.80	$962.70