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	$196.35	10.229%	$216.4346	$216.43	$216.45	$216.40
Purchase #2	$9.71	11.864%	$10.862	$10.86	$10.85	$10.90
Purchase #3	$132.75	7.429%	$142.612	$142.61	$142.60	$142.60
Purchase #4	$240.75	10.562%	$266.178	$266.18	$266.20	$266.20
Purchase #5	$84.25	6.715%	$89.9074	$89.91	$89.90	$89.90
Purchase #6	$94.47	9.540%	$103.4824	$103.48	$103.50	$103.50
Purchase #7	$91.48	11.123%	$101.6553	$101.66	$101.65	$101.70
7 purchase totals =	$849.76		$931.1317	$931.13	$931.15	$931.20