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	$97.55	8.801%	$106.1354	$106.14	$106.15	$106.10
Purchase #2	$223.31	6.775%	$238.4393	$238.44	$238.45	$238.40
Purchase #3	$155.59	5.702%	$164.4617	$164.46	$164.45	$164.50
Purchase #4	$246.38	7.634%	$265.1886	$265.19	$265.20	$265.20
Purchase #5	$164.77	10.776%	$182.5256	$182.53	$182.55	$182.50
Purchase #6	$83.47	3.595%	$86.4707	$86.47	$86.45	$86.50
Purchase #7	$98.50	10.422%	$108.7657	$108.77	$108.75	$108.80
7 purchase totals =	$1,069.57		$1,151.9870	$1,152.00	$1,152.00	$1,152.00