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	$203.86	13.484%	$231.3485	$231.35	$231.35	$231.30
Purchase #2	$136.26	11.687%	$152.1847	$152.18	$152.20	$152.20
Purchase #3	$187.64	6.834%	$200.4633	$200.46	$200.45	$200.50
Purchase #4	$10.67	4.644%	$11.1655	$11.17	$11.15	$11.20
Purchase #5	$236.80	7.661%	$254.9412	$254.94	$254.95	$254.90
Purchase #6	$119.90	9.696%	$131.5255	$131.53	$131.55	$131.50
Purchase #7	$39.69	11.508%	$44.2575	$44.26	$44.25	$44.30
7 purchase totals =	$934.82		$1,025.8862	$1,025.89	$1,025.90	$1,025.90