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	$221.95	5.351%	$233.8265	$233.83	$233.85	$233.80
Purchase #2	$198.37	8.551%	$215.3326	$215.33	$215.35	$215.30
Purchase #3	$213.95	12.772%	$241.2757	$241.28	$241.30	$241.30
Purchase #4	$184.27	8.510%	$199.9514	$199.95	$199.95	$200.00
Purchase #5	$213.84	3.620%	$221.581	$221.58	$221.60	$221.60
Purchase #6	$102.32	3.330%	$105.7273	$105.73	$105.75	$105.70
Purchase #7	$73.43	12.792%	$82.8232	$82.82	$82.80	$82.80
7 purchase totals =	$1,208.13		$1,300.5177	$1,300.52	$1,300.60	$1,300.50