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	$68.27	8.169%	$73.847	$73.85	$73.85	$73.80
Purchase #2	$101.84	11.691%	$113.7461	$113.75	$113.75	$113.70
Purchase #3	$184.35	6.712%	$196.7236	$196.72	$196.70	$196.70
Purchase #4	$220.38	11.368%	$245.4328	$245.43	$245.45	$245.40
Purchase #5	$14.35	5.645%	$15.1601	$15.16	$15.15	$15.20
Purchase #6	$66.61	8.307%	$72.1433	$72.14	$72.15	$72.10
Purchase #7	$216.60	10.272%	$238.8492	$238.85	$238.85	$238.80
7 purchase totals =	$872.40		$955.9021	$955.90	$955.90	$955.70