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	$82.84	4.831%	$86.842	$86.84	$86.85	$86.80
Purchase #2	$200.78	13.711%	$228.3089	$228.31	$228.30	$228.30
Purchase #3	$241.69	10.188%	$266.3134	$266.31	$266.30	$266.30
Purchase #4	$121.76	12.372%	$136.8241	$136.82	$136.80	$136.80
Purchase #5	$48.77	8.831%	$53.0769	$53.08	$53.10	$53.10
Purchase #6	$50.66	10.386%	$55.9215	$55.92	$55.90	$55.90
Purchase #7	$172.85	13.864%	$196.8139	$196.81	$196.80	$196.80
7 purchase totals =	$919.35		$1,024.1007	$1,024.09	$1,024.05	$1,024.00