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	$113.89	10.849%	$126.2459	$126.25	$126.25	$126.20
Purchase #2	$203.46	3.776%	$211.1426	$211.14	$211.15	$211.10
Purchase #3	$182.81	9.855%	$200.8259	$200.83	$200.85	$200.80
Purchase #4	$216.58	7.368%	$232.5376	$232.54	$232.55	$232.50
Purchase #5	$40.32	8.676%	$43.8182	$43.82	$43.80	$43.80
Purchase #6	$155.82	4.115%	$162.232	$162.23	$162.25	$162.20
Purchase #7	$148.70	10.510%	$164.3284	$164.33	$164.35	$164.30
7 purchase totals =	$1,061.58		$1,141.1306	$1,141.14	$1,141.20	$1,140.90