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	$217.99	3.518%	$225.6589	$225.66	$225.65	$225.70
Purchase #2	$125.63	4.382%	$131.1351	$131.14	$131.15	$131.10
Purchase #3	$73.86	6.766%	$78.8574	$78.86	$78.85	$78.90
Purchase #4	$182.88	7.459%	$196.521	$196.52	$196.50	$196.50
Purchase #5	$54.32	3.527%	$56.2359	$56.24	$56.25	$56.20
Purchase #6	$58.32	7.367%	$62.6164	$62.62	$62.60	$62.60
Purchase #7	$188.64	5.671%	$199.3378	$199.34	$199.35	$199.30
7 purchase totals =	$901.64		$950.3625	$950.38	$950.35	$950.30