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	$54.35	13.547%	$61.7128	$61.71	$61.70	$61.70
Purchase #2	$18.36	12.632%	$20.6792	$20.68	$20.70	$20.70
Purchase #3	$10.55	13.334%	$11.9567	$11.96	$11.95	$12.00
Purchase #4	$85.77	4.595%	$89.7111	$89.71	$89.70	$89.70
Purchase #5	$247.32	10.225%	$272.6085	$272.61	$272.60	$272.60
Purchase #6	$22.39	13.442%	$25.3997	$25.40	$25.40	$25.40
Purchase #7	$162.68	4.247%	$169.589	$169.59	$169.60	$169.60
7 purchase totals =	$601.42		$651.6570	$651.66	$651.65	$651.70