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	$76.45	12.535%	$86.033	$86.03	$86.05	$86.00
Purchase #2	$82.50	7.324%	$88.5423	$88.54	$88.55	$88.50
Purchase #3	$120.97	3.548%	$125.262	$125.26	$125.25	$125.30
Purchase #4	$198.72	10.466%	$219.518	$219.52	$219.50	$219.50
Purchase #5	$241.86	8.578%	$262.6068	$262.61	$262.60	$262.60
Purchase #6	$181.34	5.837%	$191.9248	$191.92	$191.90	$191.90
Purchase #7	$234.89	9.247%	$256.6103	$256.61	$256.60	$256.60
7 purchase totals =	$1,136.73		$1,230.4972	$1,230.49	$1,230.45	$1,230.40