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	$187.89	4.364%	$196.0895	$196.09	$196.10	$196.10
Purchase #2	$232.58	3.834%	$241.4971	$241.50	$241.50	$241.50
Purchase #3	$162.57	3.496%	$168.2534	$168.25	$168.25	$168.30
Purchase #4	$117.46	8.198%	$127.0894	$127.09	$127.10	$127.10
Purchase #5	$127.45	3.746%	$132.2243	$132.22	$132.20	$132.20
Purchase #6	$116.33	7.287%	$124.807	$124.81	$124.80	$124.80
Purchase #7	$222.90	10.430%	$246.1485	$246.15	$246.15	$246.10
7 purchase totals =	$1,167.18		$1,236.1092	$1,236.11	$1,236.10	$1,236.10