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	$178.29	10.213%	$196.4988	$196.50	$196.50	$196.50
Purchase #2	$33.83	11.671%	$37.7783	$37.78	$37.80	$37.80
Purchase #3	$231.27	13.372%	$262.1954	$262.20	$262.20	$262.20
Purchase #4	$54.82	12.329%	$61.5788	$61.58	$61.60	$61.60
Purchase #5	$184.53	8.275%	$199.7999	$199.80	$199.80	$199.80
Purchase #6	$13.65	3.828%	$14.1725	$14.17	$14.15	$14.20
Purchase #7	$238.98	7.470%	$256.8318	$256.83	$256.85	$256.80
7 purchase totals =	$935.37		$1,028.8555	$1,028.86	$1,028.90	$1,028.90