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	$116.30	13.158%	$131.6028	$131.60	$131.60	$131.60
Purchase #2	$176.25	3.315%	$182.0927	$182.09	$182.10	$182.10
Purchase #3	$7.43	5.412%	$7.8321	$7.83	$7.85	$7.80
Purchase #4	$196.25	4.696%	$205.4659	$205.47	$205.45	$205.50
Purchase #5	$235.77	9.127%	$257.2887	$257.29	$257.30	$257.30
Purchase #6	$116.91	3.448%	$120.9411	$120.94	$120.95	$120.90
Purchase #7	$157.60	4.403%	$164.5391	$164.54	$164.55	$164.50
7 purchase totals =	$1,006.51		$1,069.7624	$1,069.76	$1,069.80	$1,069.70