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	$208.50	13.772%	$237.2146	$237.21	$237.20	$237.20
Purchase #2	$98.59	7.102%	$105.5919	$105.59	$105.60	$105.60
Purchase #3	$72.94	7.656%	$78.5243	$78.52	$78.50	$78.50
Purchase #4	$153.90	11.535%	$171.6524	$171.65	$171.65	$171.70
Purchase #5	$128.38	10.792%	$142.2348	$142.23	$142.25	$142.20
Purchase #6	$136.65	10.401%	$150.863	$150.86	$150.85	$150.90
Purchase #7	$196.37	7.444%	$210.9878	$210.99	$211.00	$211.00
7 purchase totals =	$995.33		$1,097.0688	$1,097.05	$1,097.05	$1,097.10