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	$113.93	9.421%	$124.6633	$124.66	$124.65	$124.70
Purchase #2	$101.67	7.724%	$109.523	$109.52	$109.50	$109.50
Purchase #3	$243.64	6.711%	$259.9907	$259.99	$260.00	$260.00
Purchase #4	$209.50	12.419%	$235.5178	$235.52	$235.50	$235.50
Purchase #5	$180.56	5.529%	$190.5432	$190.54	$190.55	$190.50
Purchase #6	$29.58	10.188%	$32.5936	$32.59	$32.60	$32.60
Purchase #7	$103.42	5.558%	$109.1681	$109.17	$109.15	$109.20
7 purchase totals =	$982.30		$1,061.9997	$1,061.99	$1,061.95	$1,062.00