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	$12.81	12.638%	$14.4289	$14.43	$14.45	$14.40
Purchase #2	$158.64	10.709%	$175.6288	$175.63	$175.65	$175.60
Purchase #3	$236.94	3.545%	$245.3395	$245.34	$245.35	$245.30
Purchase #4	$109.72	9.278%	$119.8998	$119.90	$119.90	$119.90
Purchase #5	$13.91	3.288%	$14.3674	$14.37	$14.35	$14.40
Purchase #6	$150.48	11.163%	$167.2781	$167.28	$167.30	$167.30
Purchase #7	$250.53	12.678%	$282.2922	$282.29	$282.30	$282.30
7 purchase totals =	$933.03		$1,019.2347	$1,019.24	$1,019.30	$1,019.20