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	$119.46	10.861%	$132.4346	$132.43	$132.45	$132.40
Purchase #2	$117.34	5.170%	$123.4065	$123.41	$123.40	$123.40
Purchase #3	$14.34	7.789%	$15.4569	$15.46	$15.45	$15.50
Purchase #4	$137.77	7.788%	$148.4995	$148.50	$148.50	$148.50
Purchase #5	$67.30	7.479%	$72.3334	$72.33	$72.35	$72.30
Purchase #6	$164.25	11.267%	$182.756	$182.76	$182.75	$182.80
Purchase #7	$84.66	7.702%	$91.1805	$91.18	$91.20	$91.20
7 purchase totals =	$705.12		$766.0674	$766.07	$766.10	$766.10