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	$198.80	4.864%	$208.4696	$208.47	$208.45	$208.50
Purchase #2	$29.34	6.701%	$31.3061	$31.31	$31.30	$31.30
Purchase #3	$225.90	13.650%	$256.7354	$256.74	$256.75	$256.70
Purchase #4	$106.30	10.578%	$117.5444	$117.54	$117.55	$117.50
Purchase #5	$149.94	13.861%	$170.7232	$170.72	$170.70	$170.70
Purchase #6	$47.99	13.490%	$54.4639	$54.46	$54.45	$54.50
Purchase #7	$166.39	11.655%	$185.7828	$185.78	$185.80	$185.80
7 purchase totals =	$924.66		$1,025.0254	$1,025.02	$1,025.00	$1,025.00