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	$170.89	6.830%	$182.5618	$182.56	$182.55	$182.60
Purchase #2	$173.43	6.149%	$184.0942	$184.09	$184.10	$184.10
Purchase #3	$139.40	13.653%	$158.4323	$158.43	$158.45	$158.40
Purchase #4	$237.32	7.654%	$255.4845	$255.48	$255.50	$255.50
Purchase #5	$194.41	13.808%	$221.2541	$221.25	$221.25	$221.30
Purchase #6	$182.45	7.111%	$195.424	$195.42	$195.40	$195.40
Purchase #7	$242.35	10.276%	$267.2539	$267.25	$267.25	$267.30
7 purchase totals =	$1,340.25		$1,464.5048	$1,464.48	$1,464.50	$1,464.60