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	$105.62	4.554%	$110.4299	$110.43	$110.45	$110.40
Purchase #2	$41.86	4.613%	$43.791	$43.79	$43.80	$43.80
Purchase #3	$38.62	10.866%	$42.8164	$42.82	$42.80	$42.80
Purchase #4	$196.42	5.329%	$206.8872	$206.89	$206.90	$206.90
Purchase #5	$174.82	6.689%	$186.5137	$186.51	$186.50	$186.50
Purchase #6	$39.65	6.850%	$42.366	$42.37	$42.35	$42.40
Purchase #7	$80.70	12.861%	$91.0788	$91.08	$91.10	$91.10
7 purchase totals =	$677.69		$723.8830	$723.89	$723.90	$723.90