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	$116.40	8.681%	$126.5047	$126.50	$126.50	$126.50
Purchase #2	$224.25	8.605%	$243.5467	$243.55	$243.55	$243.50
Purchase #3	$60.26	12.488%	$67.7853	$67.79	$67.80	$67.80
Purchase #4	$206.93	3.420%	$214.007	$214.01	$214.00	$214.00
Purchase #5	$46.29	13.497%	$52.5378	$52.54	$52.55	$52.50
Purchase #6	$196.67	13.435%	$223.0926	$223.09	$223.10	$223.10
Purchase #7	$152.66	4.448%	$159.4503	$159.45	$159.45	$159.50
7 purchase totals =	$1,003.46		$1,086.9244	$1,086.93	$1,086.95	$1,086.90