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	$98.48	13.463%	$111.7384	$111.74	$111.75	$111.70
Purchase #2	$53.99	6.587%	$57.5463	$57.55	$57.55	$57.50
Purchase #3	$201.39	5.504%	$212.4745	$212.47	$212.45	$212.50
Purchase #4	$95.60	10.471%	$105.6103	$105.61	$105.60	$105.60
Purchase #5	$210.69	9.501%	$230.7077	$230.71	$230.70	$230.70
Purchase #6	$217.79	7.834%	$234.8517	$234.85	$234.85	$234.90
Purchase #7	$108.48	13.461%	$123.0825	$123.08	$123.10	$123.10
7 purchase totals =	$986.42		$1,076.0114	$1,076.01	$1,076.00	$1,076.00