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	$102.96	7.872%	$111.065	$111.07	$111.05	$111.10
Purchase #2	$180.92	13.535%	$205.4075	$205.41	$205.40	$205.40
Purchase #3	$180.44	10.606%	$199.5775	$199.58	$199.60	$199.60
Purchase #4	$214.32	5.715%	$226.5684	$226.57	$226.55	$226.60
Purchase #5	$194.39	12.558%	$218.8015	$218.80	$218.80	$218.80
Purchase #6	$39.83	5.662%	$42.0852	$42.09	$42.10	$42.10
Purchase #7	$101.37	11.789%	$113.3205	$113.32	$113.30	$113.30
7 purchase totals =	$1,014.23		$1,116.8256	$1,116.84	$1,116.80	$1,116.90