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	$69.78	3.242%	$72.0423	$72.04	$72.05	$72.00
Purchase #2	$40.39	5.448%	$42.5904	$42.59	$42.60	$42.60
Purchase #3	$24.50	7.466%	$26.3292	$26.33	$26.35	$26.30
Purchase #4	$87.32	8.317%	$94.5824	$94.58	$94.60	$94.60
Purchase #5	$187.33	6.509%	$199.5233	$199.52	$199.50	$199.50
Purchase #6	$99.34	12.694%	$111.9502	$111.95	$111.95	$112.00
Purchase #7	$135.25	9.408%	$147.9743	$147.97	$147.95	$148.00
7 purchase totals =	$643.91		$694.9921	$694.98	$695.00	$695.00