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	$98.37	9.635%	$107.8479	$107.85	$107.85	$107.80
Purchase #2	$80.49	11.537%	$89.7761	$89.78	$89.80	$89.80
Purchase #3	$174.51	12.660%	$196.603	$196.60	$196.60	$196.60
Purchase #4	$167.38	9.373%	$183.0685	$183.07	$183.05	$183.10
Purchase #5	$138.34	9.619%	$151.6469	$151.65	$151.65	$151.60
Purchase #6	$198.60	9.441%	$217.3498	$217.35	$217.35	$217.30
Purchase #7	$232.70	3.630%	$241.147	$241.15	$241.15	$241.10
7 purchase totals =	$1,090.39		$1,187.4392	$1,187.45	$1,187.45	$1,187.30