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	$249.61	4.648%	$261.2119	$261.21	$261.20	$261.20
Purchase #2	$171.90	13.197%	$194.5856	$194.59	$194.60	$194.60
Purchase #3	$80.39	7.629%	$86.523	$86.52	$86.50	$86.50
Purchase #4	$126.90	10.460%	$140.1737	$140.17	$140.15	$140.20
Purchase #5	$230.39	7.341%	$247.3029	$247.30	$247.30	$247.30
Purchase #6	$50.37	6.409%	$53.5982	$53.60	$53.60	$53.60
Purchase #7	$48.47	6.437%	$51.59	$51.59	$51.60	$51.60
7 purchase totals =	$958.03		$1,034.9853	$1,034.98	$1,034.95	$1,035.00