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	$48.80	8.765%	$53.0773	$53.08	$53.10	$53.10
Purchase #2	$150.38	4.142%	$156.6087	$156.61	$156.60	$156.60
Purchase #3	$245.64	6.407%	$261.3782	$261.38	$261.40	$261.40
Purchase #4	$158.38	12.601%	$178.3375	$178.34	$178.35	$178.30
Purchase #5	$145.72	6.812%	$155.6464	$155.65	$155.65	$155.60
Purchase #6	$224.36	8.596%	$243.646	$243.65	$243.65	$243.60
Purchase #7	$43.81	5.872%	$46.3825	$46.38	$46.40	$46.40
7 purchase totals =	$1,017.09		$1,095.0766	$1,095.09	$1,095.15	$1,095.00