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	$76.26	12.688%	$85.9359	$85.94	$85.95	$85.90
Purchase #2	$169.92	7.832%	$183.2281	$183.23	$183.25	$183.20
Purchase #3	$6.27	12.140%	$7.0312	$7.03	$7.05	$7.00
Purchase #4	$7.48	4.638%	$7.8269	$7.83	$7.85	$7.80
Purchase #5	$81.51	4.374%	$85.0752	$85.08	$85.10	$85.10
Purchase #6	$108.63	13.478%	$123.2712	$123.27	$123.25	$123.30
Purchase #7	$223.94	9.229%	$244.6074	$244.61	$244.60	$244.60
7 purchase totals =	$674.01		$736.9759	$736.99	$737.05	$736.90