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	$116.74	8.395%	$126.5403	$126.54	$126.55	$126.50
Purchase #2	$164.30	3.542%	$170.1195	$170.12	$170.10	$170.10
Purchase #3	$141.50	7.555%	$152.1903	$152.19	$152.20	$152.20
Purchase #4	$96.70	8.651%	$105.0655	$105.07	$105.05	$105.10
Purchase #5	$37.92	13.140%	$42.9027	$42.90	$42.90	$42.90
Purchase #6	$108.67	7.353%	$116.6605	$116.66	$116.65	$116.70
Purchase #7	$10.69	7.817%	$11.5256	$11.53	$11.55	$11.50
7 purchase totals =	$676.52		$725.0044	$725.01	$725.00	$725.00