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	$157.65	11.679%	$176.0619	$176.06	$176.05	$176.10
Purchase #2	$156.38	12.758%	$176.331	$176.33	$176.35	$176.30
Purchase #3	$31.83	9.571%	$34.8764	$34.88	$34.90	$34.90
Purchase #4	$243.78	13.332%	$276.2807	$276.28	$276.30	$276.30
Purchase #5	$164.81	12.805%	$185.9139	$185.91	$185.90	$185.90
Purchase #6	$25.56	9.472%	$27.981	$27.98	$28.00	$28.00
Purchase #7	$224.77	4.490%	$234.8622	$234.86	$234.85	$234.90
7 purchase totals =	$1,004.78		$1,112.3071	$1,112.30	$1,112.35	$1,112.40