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	$196.91	13.416%	$223.3274	$223.33	$223.35	$223.30
Purchase #2	$164.71	10.138%	$181.4083	$181.41	$181.40	$181.40
Purchase #3	$201.55	5.779%	$213.1976	$213.20	$213.20	$213.20
Purchase #4	$48.90	4.307%	$51.0061	$51.01	$51.00	$51.00
Purchase #5	$136.69	7.109%	$146.4073	$146.41	$146.40	$146.40
Purchase #6	$35.65	5.297%	$37.5384	$37.54	$37.55	$37.50
Purchase #7	$235.43	3.382%	$243.3922	$243.39	$243.40	$243.40
7 purchase totals =	$1,019.84		$1,096.2773	$1,096.29	$1,096.30	$1,096.20