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	$216.52	7.707%	$233.2072	$233.21	$233.20	$233.20
Purchase #2	$116.89	12.244%	$131.202	$131.20	$131.20	$131.20
Purchase #3	$79.52	12.752%	$89.6604	$89.66	$89.65	$89.70
Purchase #4	$248.98	4.827%	$260.9983	$261.00	$261.00	$261.00
Purchase #5	$228.62	12.320%	$256.786	$256.79	$256.80	$256.80
Purchase #6	$190.72	6.688%	$203.4754	$203.48	$203.50	$203.50
Purchase #7	$82.64	7.158%	$88.5554	$88.56	$88.55	$88.60
7 purchase totals =	$1,163.89		$1,263.8847	$1,263.90	$1,263.90	$1,264.00