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	$51.36	10.342%	$56.6717	$56.67	$56.65	$56.70
Purchase #2	$206.77	4.529%	$216.1346	$216.13	$216.15	$216.10
Purchase #3	$56.31	11.834%	$62.9737	$62.97	$62.95	$63.00
Purchase #4	$119.84	10.518%	$132.4448	$132.44	$132.45	$132.40
Purchase #5	$208.67	6.508%	$222.2502	$222.25	$222.25	$222.30
Purchase #6	$137.98	9.507%	$151.0978	$151.10	$151.10	$151.10
Purchase #7	$196.80	10.740%	$217.9363	$217.94	$217.95	$217.90
7 purchase totals =	$977.73		$1,059.5091	$1,059.50	$1,059.50	$1,059.50