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	$190.59	9.580%	$208.8485	$208.85	$208.85	$208.80
Purchase #2	$34.90	4.742%	$36.555	$36.56	$36.55	$36.60
Purchase #3	$185.96	10.378%	$205.2589	$205.26	$205.25	$205.30
Purchase #4	$145.97	12.469%	$164.171	$164.17	$164.15	$164.20
Purchase #5	$119.51	6.536%	$127.3212	$127.32	$127.30	$127.30
Purchase #6	$175.83	5.723%	$185.8928	$185.89	$185.90	$185.90
Purchase #7	$15.65	12.154%	$17.5521	$17.55	$17.55	$17.60
7 purchase totals =	$868.41		$945.5995	$945.60	$945.55	$945.70