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	$167.93	5.300%	$176.8303	$176.83	$176.85	$176.80
Purchase #2	$7.35	11.621%	$8.2041	$8.20	$8.20	$8.20
Purchase #3	$132.49	5.282%	$139.4881	$139.49	$139.50	$139.50
Purchase #4	$183.59	4.324%	$191.5284	$191.53	$191.55	$191.50
Purchase #5	$173.61	6.869%	$185.5353	$185.54	$185.55	$185.50
Purchase #6	$61.44	10.110%	$67.6516	$67.65	$67.65	$67.70
Purchase #7	$232.72	3.781%	$241.5191	$241.52	$241.50	$241.50
7 purchase totals =	$959.13		$1,010.7569	$1,010.76	$1,010.80	$1,010.70