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	$148.89	9.228%	$162.6296	$162.63	$162.65	$162.60
Purchase #2	$174.53	12.504%	$196.3532	$196.35	$196.35	$196.40
Purchase #3	$189.89	5.818%	$200.9378	$200.94	$200.95	$200.90
Purchase #4	$73.67	12.571%	$82.9311	$82.93	$82.95	$82.90
Purchase #5	$129.29	5.151%	$135.9497	$135.95	$135.95	$135.90
Purchase #6	$14.64	7.262%	$15.7032	$15.70	$15.70	$15.70
Purchase #7	$234.61	8.676%	$254.9648	$254.96	$254.95	$255.00
7 purchase totals =	$965.52		$1,049.4694	$1,049.46	$1,049.50	$1,049.40