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	$17.54	9.356%	$19.181	$19.18	$19.20	$19.20
Purchase #2	$63.64	13.622%	$72.309	$72.31	$72.30	$72.30
Purchase #3	$60.52	7.296%	$64.9355	$64.94	$64.95	$64.90
Purchase #4	$90.93	5.336%	$95.782	$95.78	$95.80	$95.80
Purchase #5	$171.85	6.677%	$183.3244	$183.32	$183.30	$183.30
Purchase #6	$195.97	6.379%	$208.4709	$208.47	$208.45	$208.50
Purchase #7	$102.38	6.721%	$109.261	$109.26	$109.25	$109.30
7 purchase totals =	$702.83		$753.2638	$753.26	$753.25	$753.30