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	$179.73	9.351%	$196.5366	$196.54	$196.55	$196.50
Purchase #2	$28.57	11.534%	$31.8653	$31.87	$31.85	$31.90
Purchase #3	$199.26	5.534%	$210.287	$210.29	$210.30	$210.30
Purchase #4	$41.42	13.730%	$47.107	$47.11	$47.10	$47.10
Purchase #5	$120.33	3.659%	$124.7329	$124.73	$124.75	$124.70
Purchase #6	$224.86	13.517%	$255.2543	$255.25	$255.25	$255.30
Purchase #7	$76.35	4.332%	$79.6575	$79.66	$79.65	$79.70
7 purchase totals =	$870.52		$945.4406	$945.45	$945.45	$945.50