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	$217.56	8.776%	$236.6531	$236.65	$236.65	$236.70
Purchase #2	$95.63	5.157%	$100.5616	$100.56	$100.55	$100.60
Purchase #3	$50.60	13.455%	$57.4082	$57.41	$57.40	$57.40
Purchase #4	$119.72	4.172%	$124.7147	$124.71	$124.70	$124.70
Purchase #5	$43.49	4.345%	$45.3796	$45.38	$45.40	$45.40
Purchase #6	$72.25	13.852%	$82.2581	$82.26	$82.25	$82.30
Purchase #7	$67.73	13.357%	$76.7767	$76.78	$76.80	$76.80
7 purchase totals =	$666.98		$723.7520	$723.75	$723.75	$723.90