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	$44.59	6.705%	$47.5798	$47.58	$47.60	$47.60
Purchase #2	$224.69	3.717%	$233.0417	$233.04	$233.05	$233.00
Purchase #3	$167.82	5.412%	$176.9024	$176.90	$176.90	$176.90
Purchase #4	$68.72	11.356%	$76.5238	$76.52	$76.50	$76.50
Purchase #5	$139.64	6.665%	$148.947	$148.95	$148.95	$148.90
Purchase #6	$108.83	13.464%	$123.4829	$123.48	$123.50	$123.50
Purchase #7	$82.68	7.674%	$89.0249	$89.02	$89.00	$89.00
7 purchase totals =	$836.97		$895.5025	$895.49	$895.50	$895.40