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	$97.52	7.738%	$105.0661	$105.07	$105.05	$105.10
Purchase #2	$6.25	11.719%	$6.9824	$6.98	$7.00	$7.00
Purchase #3	$86.74	4.322%	$90.4889	$90.49	$90.50	$90.50
Purchase #4	$101.65	7.457%	$109.23	$109.23	$109.25	$109.20
Purchase #5	$122.62	4.777%	$128.4776	$128.48	$128.50	$128.50
Purchase #6	$135.43	4.287%	$141.2359	$141.24	$141.25	$141.20
Purchase #7	$131.66	6.716%	$140.5023	$140.50	$140.50	$140.50
7 purchase totals =	$681.87		$721.9832	$721.99	$722.05	$722.00