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	$68.87	11.554%	$76.8272	$76.83	$76.85	$76.80
Purchase #2	$72.79	13.267%	$82.447	$82.45	$82.45	$82.40
Purchase #3	$67.30	5.139%	$70.7585	$70.76	$70.75	$70.80
Purchase #4	$19.44	12.555%	$21.8807	$21.88	$21.90	$21.90
Purchase #5	$107.36	8.551%	$116.5404	$116.54	$116.55	$116.50
Purchase #6	$137.29	13.454%	$155.761	$155.76	$155.75	$155.80
Purchase #7	$171.50	13.840%	$195.2356	$195.24	$195.25	$195.20
7 purchase totals =	$644.55		$719.4504	$719.46	$719.50	$719.40