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	$57.71	8.398%	$62.5565	$62.56	$62.55	$62.60
Purchase #2	$190.42	7.563%	$204.8215	$204.82	$204.80	$204.80
Purchase #3	$78.28	10.569%	$86.5534	$86.55	$86.55	$86.60
Purchase #4	$187.85	4.405%	$196.1248	$196.12	$196.10	$196.10
Purchase #5	$31.99	5.687%	$33.8093	$33.81	$33.80	$33.80
Purchase #6	$145.99	10.257%	$160.9642	$160.96	$160.95	$161.00
Purchase #7	$51.48	10.661%	$56.9683	$56.97	$56.95	$57.00
7 purchase totals =	$743.72		$801.7980	$801.79	$801.70	$801.90