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	$174.82	10.570%	$193.2985	$193.30	$193.30	$193.30
Purchase #2	$12.69	7.176%	$13.6006	$13.60	$13.60	$13.60
Purchase #3	$171.31	13.694%	$194.7692	$194.77	$194.75	$194.80
Purchase #4	$86.83	6.639%	$92.5946	$92.59	$92.60	$92.60
Purchase #5	$194.84	5.442%	$205.4432	$205.44	$205.45	$205.40
Purchase #6	$183.40	7.186%	$196.5791	$196.58	$196.60	$196.60
Purchase #7	$219.82	3.860%	$228.3051	$228.31	$228.30	$228.30
7 purchase totals =	$1,043.71		$1,124.5903	$1,124.59	$1,124.60	$1,124.60