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	$164.65	10.783%	$182.4042	$182.40	$182.40	$182.40
Purchase #2	$108.56	13.536%	$123.2547	$123.25	$123.25	$123.30
Purchase #3	$21.75	5.449%	$22.9352	$22.94	$22.95	$22.90
Purchase #4	$181.30	10.524%	$200.38	$200.38	$200.40	$200.40
Purchase #5	$131.81	3.737%	$136.7357	$136.74	$136.75	$136.70
Purchase #6	$208.37	5.434%	$219.6928	$219.69	$219.70	$219.70
Purchase #7	$195.79	12.183%	$219.6431	$219.64	$219.65	$219.60
7 purchase totals =	$1,012.23		$1,105.0457	$1,105.04	$1,105.10	$1,105.00