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	$156.47	7.274%	$167.8516	$167.85	$167.85	$167.90
Purchase #2	$49.98	7.731%	$53.844	$53.84	$53.85	$53.80
Purchase #3	$158.57	6.288%	$168.5409	$168.54	$168.55	$168.50
Purchase #4	$180.62	8.775%	$196.4694	$196.47	$196.45	$196.50
Purchase #5	$84.75	13.105%	$95.8565	$95.86	$95.85	$95.90
Purchase #6	$212.55	13.673%	$241.612	$241.61	$241.60	$241.60
Purchase #7	$125.94	6.129%	$133.6589	$133.66	$133.65	$133.70
7 purchase totals =	$968.88		$1,057.8333	$1,057.83	$1,057.80	$1,057.90