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	$216.61	3.444%	$224.07	$224.07	$224.05	$224.10
Purchase #2	$12.75	5.299%	$13.4256	$13.43	$13.45	$13.40
Purchase #3	$106.88	6.354%	$113.6712	$113.67	$113.65	$113.70
Purchase #4	$189.85	13.665%	$215.793	$215.79	$215.80	$215.80
Purchase #5	$77.27	10.686%	$85.5271	$85.53	$85.55	$85.50
Purchase #6	$54.34	13.307%	$61.571	$61.57	$61.55	$61.60
Purchase #7	$54.30	5.384%	$57.2235	$57.22	$57.20	$57.20
7 purchase totals =	$712.00		$771.2814	$771.28	$771.25	$771.30