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	$241.43	10.806%	$267.5189	$267.52	$267.50	$267.50
Purchase #2	$200.88	12.453%	$225.8956	$225.90	$225.90	$225.90
Purchase #3	$12.67	7.469%	$13.6163	$13.62	$13.60	$13.60
Purchase #4	$215.51	13.195%	$243.9465	$243.95	$243.95	$243.90
Purchase #5	$64.32	8.867%	$70.0233	$70.02	$70.00	$70.00
Purchase #6	$164.59	8.475%	$178.539	$178.54	$178.55	$178.50
Purchase #7	$66.33	9.874%	$72.8794	$72.88	$72.90	$72.90
7 purchase totals =	$965.73		$1,072.4190	$1,072.43	$1,072.40	$1,072.30