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	$79.32	9.591%	$86.9276	$86.93	$86.95	$86.90
Purchase #2	$153.60	3.147%	$158.4338	$158.43	$158.45	$158.40
Purchase #3	$44.53	3.765%	$46.2066	$46.21	$46.20	$46.20
Purchase #4	$76.52	12.194%	$85.8508	$85.85	$85.85	$85.90
Purchase #5	$144.34	6.361%	$153.5215	$153.52	$153.50	$153.50
Purchase #6	$36.93	4.317%	$38.5243	$38.52	$38.50	$38.50
Purchase #7	$134.97	6.699%	$144.0116	$144.01	$144.00	$144.00
7 purchase totals =	$670.21		$713.4762	$713.47	$713.45	$713.40