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	$69.68	4.235%	$72.6309	$72.63	$72.65	$72.60
Purchase #2	$212.38	13.659%	$241.389	$241.39	$241.40	$241.40
Purchase #3	$6.37	10.156%	$7.0169	$7.02	$7.00	$7.00
Purchase #4	$234.52	6.510%	$249.7873	$249.79	$249.80	$249.80
Purchase #5	$89.33	12.417%	$100.4221	$100.42	$100.40	$100.40
Purchase #6	$176.97	5.832%	$187.2909	$187.29	$187.30	$187.30
Purchase #7	$176.50	3.690%	$183.0129	$183.01	$183.00	$183.00
7 purchase totals =	$965.75		$1,041.5500	$1,041.55	$1,041.55	$1,041.50