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	$78.42	4.547%	$81.9858	$81.99	$82.00	$82.00
Purchase #2	$25.90	11.307%	$28.8285	$28.83	$28.85	$28.80
Purchase #3	$182.57	7.392%	$196.0656	$196.07	$196.05	$196.10
Purchase #4	$222.78	10.790%	$246.818	$246.82	$246.80	$246.80
Purchase #5	$228.69	8.350%	$247.7856	$247.79	$247.80	$247.80
Purchase #6	$86.57	3.236%	$89.3714	$89.37	$89.35	$89.40
Purchase #7	$136.37	4.128%	$141.9994	$142.00	$142.00	$142.00
7 purchase totals =	$961.30		$1,032.8543	$1,032.87	$1,032.85	$1,032.90