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	$12.76	13.232%	$14.4484	$14.45	$14.45	$14.40
Purchase #2	$158.50	13.704%	$180.2208	$180.22	$180.20	$180.20
Purchase #3	$245.56	4.596%	$256.8459	$256.85	$256.85	$256.80
Purchase #4	$198.34	7.870%	$213.9494	$213.95	$213.95	$213.90
Purchase #5	$56.83	4.821%	$59.5698	$59.57	$59.55	$59.60
Purchase #6	$71.25	13.330%	$80.7476	$80.75	$80.75	$80.70
Purchase #7	$229.96	3.595%	$238.2271	$238.23	$238.25	$238.20
7 purchase totals =	$973.20		$1,044.0090	$1,044.02	$1,044.00	$1,043.80