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	$161.37	8.364%	$174.867	$174.87	$174.85	$174.90
Purchase #2	$10.81	9.667%	$11.855	$11.86	$11.85	$11.90
Purchase #3	$168.31	3.806%	$174.7159	$174.72	$174.70	$174.70
Purchase #4	$132.31	3.802%	$137.3404	$137.34	$137.35	$137.30
Purchase #5	$196.29	13.360%	$222.5143	$222.51	$222.50	$222.50
Purchase #6	$105.55	6.172%	$112.0645	$112.06	$112.05	$112.10
Purchase #7	$65.90	7.753%	$71.0092	$71.01	$71.00	$71.00
7 purchase totals =	$840.54		$904.3663	$904.37	$904.30	$904.40