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	$147.90	7.397%	$158.8402	$158.84	$158.85	$158.80
Purchase #2	$193.92	12.566%	$218.288	$218.29	$218.30	$218.30
Purchase #3	$15.78	12.127%	$17.6936	$17.69	$17.70	$17.70
Purchase #4	$16.78	12.858%	$18.9376	$18.94	$18.95	$18.90
Purchase #5	$178.83	3.743%	$185.5236	$185.52	$185.50	$185.50
Purchase #6	$100.90	13.488%	$114.5094	$114.51	$114.50	$114.50
Purchase #7	$209.88	4.481%	$219.2847	$219.28	$219.30	$219.30
7 purchase totals =	$863.99		$933.0771	$933.07	$933.10	$933.00