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	$193.68	13.473%	$219.7745	$219.77	$219.75	$219.80
Purchase #2	$164.64	10.329%	$181.6457	$181.65	$181.65	$181.60
Purchase #3	$76.64	11.732%	$85.6314	$85.63	$85.65	$85.60
Purchase #4	$131.37	9.786%	$144.2259	$144.23	$144.25	$144.20
Purchase #5	$96.66	9.536%	$105.8775	$105.88	$105.90	$105.90
Purchase #6	$232.83	5.570%	$245.7986	$245.80	$245.80	$245.80
Purchase #7	$142.30	13.559%	$161.5945	$161.59	$161.60	$161.60
7 purchase totals =	$1,038.12		$1,144.5481	$1,144.55	$1,144.60	$1,144.50