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	$172.34	13.730%	$196.0023	$196.00	$196.00	$196.00
Purchase #2	$137.85	11.312%	$153.4436	$153.44	$153.45	$153.40
Purchase #3	$91.58	13.757%	$104.1787	$104.18	$104.20	$104.20
Purchase #4	$198.46	3.370%	$205.1481	$205.15	$205.15	$205.10
Purchase #5	$204.94	12.577%	$230.7153	$230.72	$230.70	$230.70
Purchase #6	$137.43	9.439%	$150.402	$150.40	$150.40	$150.40
Purchase #7	$68.38	4.859%	$71.7026	$71.70	$71.70	$71.70
7 purchase totals =	$1,010.98		$1,111.5926	$1,111.59	$1,111.60	$1,111.50