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	$97.71	13.541%	$110.9409	$110.94	$110.95	$110.90
Purchase #2	$231.35	10.599%	$255.8708	$255.87	$255.85	$255.90
Purchase #3	$249.74	12.495%	$280.945	$280.95	$280.95	$280.90
Purchase #4	$226.85	10.158%	$249.8934	$249.89	$249.90	$249.90
Purchase #5	$40.76	10.189%	$44.913	$44.91	$44.90	$44.90
Purchase #6	$83.99	7.808%	$90.5479	$90.55	$90.55	$90.50
Purchase #7	$25.37	11.774%	$28.3571	$28.36	$28.35	$28.40
7 purchase totals =	$955.77		$1,061.4681	$1,061.47	$1,061.45	$1,061.40