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	$131.28	8.695%	$142.6948	$142.69	$142.70	$142.70
Purchase #2	$88.44	11.493%	$98.6044	$98.60	$98.60	$98.60
Purchase #3	$194.36	7.404%	$208.7504	$208.75	$208.75	$208.80
Purchase #4	$62.64	3.781%	$65.0084	$65.01	$65.00	$65.00
Purchase #5	$138.61	9.408%	$151.6504	$151.65	$151.65	$151.70
Purchase #6	$128.73	11.348%	$143.3383	$143.34	$143.35	$143.30
Purchase #7	$139.29	9.433%	$152.4292	$152.43	$152.45	$152.40
7 purchase totals =	$883.35		$962.4759	$962.47	$962.50	$962.50