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	$91.38	13.214%	$103.455	$103.46	$103.45	$103.50
Purchase #2	$227.66	13.583%	$258.5831	$258.58	$258.60	$258.60
Purchase #3	$199.97	8.723%	$217.4134	$217.41	$217.40	$217.40
Purchase #4	$10.53	3.368%	$10.8847	$10.88	$10.90	$10.90
Purchase #5	$244.71	9.745%	$268.557	$268.56	$268.55	$268.60
Purchase #6	$52.82	6.499%	$56.2528	$56.25	$56.25	$56.30
Purchase #7	$103.82	3.402%	$107.352	$107.35	$107.35	$107.40
7 purchase totals =	$930.89		$1,022.4980	$1,022.49	$1,022.50	$1,022.70