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	$23.39	9.292%	$25.5634	$25.56	$25.55	$25.60
Purchase #2	$43.82	8.446%	$47.521	$47.52	$47.50	$47.50
Purchase #3	$229.83	11.201%	$255.5733	$255.57	$255.55	$255.60
Purchase #4	$119.77	3.139%	$123.5296	$123.53	$123.55	$123.50
Purchase #5	$110.27	4.221%	$114.9245	$114.92	$114.90	$114.90
Purchase #6	$182.27	7.433%	$195.8181	$195.82	$195.80	$195.80
Purchase #7	$238.49	5.371%	$251.2993	$251.30	$251.30	$251.30
7 purchase totals =	$947.84		$1,014.2292	$1,014.22	$1,014.15	$1,014.20