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	$75.97	9.158%	$82.9273	$82.93	$82.95	$82.90
Purchase #2	$166.81	9.263%	$182.2616	$182.26	$182.25	$182.30
Purchase #3	$46.78	5.661%	$49.4282	$49.43	$49.45	$49.40
Purchase #4	$246.93	11.295%	$274.8207	$274.82	$274.80	$274.80
Purchase #5	$196.90	7.528%	$211.7226	$211.72	$211.70	$211.70
Purchase #6	$54.99	13.613%	$62.4758	$62.48	$62.50	$62.50
Purchase #7	$147.31	5.348%	$155.1881	$155.19	$155.20	$155.20
7 purchase totals =	$935.69		$1,018.8243	$1,018.83	$1,018.85	$1,018.80