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	$82.52	3.460%	$85.3752	$85.38	$85.40	$85.40
Purchase #2	$186.47	11.547%	$208.0017	$208.00	$208.00	$208.00
Purchase #3	$12.25	6.725%	$13.0738	$13.07	$13.05	$13.10
Purchase #4	$39.83	4.538%	$41.6375	$41.64	$41.65	$41.60
Purchase #5	$108.69	10.242%	$119.822	$119.82	$119.80	$119.80
Purchase #6	$176.73	6.601%	$188.3959	$188.40	$188.40	$188.40
Purchase #7	$93.63	5.253%	$98.5484	$98.55	$98.55	$98.50
7 purchase totals =	$700.12		$754.8545	$754.86	$754.85	$754.80