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	$219.75	11.280%	$244.5378	$244.54	$244.55	$244.50
Purchase #2	$210.46	4.290%	$219.4887	$219.49	$219.50	$219.50
Purchase #3	$179.97	5.863%	$190.5216	$190.52	$190.50	$190.50
Purchase #4	$80.88	5.777%	$85.5524	$85.55	$85.55	$85.60
Purchase #5	$170.34	7.150%	$182.5193	$182.52	$182.50	$182.50
Purchase #6	$119.83	13.497%	$136.0035	$136.00	$136.00	$136.00
Purchase #7	$101.41	4.224%	$105.6936	$105.69	$105.70	$105.70
7 purchase totals =	$1,082.64		$1,164.3169	$1,164.31	$1,164.30	$1,164.30