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	$172.75	13.512%	$196.092	$196.09	$196.10	$196.10
Purchase #2	$106.75	6.756%	$113.962	$113.96	$113.95	$114.00
Purchase #3	$18.71	8.718%	$20.3411	$20.34	$20.35	$20.30
Purchase #4	$22.63	11.371%	$25.2033	$25.20	$25.20	$25.20
Purchase #5	$218.61	10.311%	$241.1509	$241.15	$241.15	$241.20
Purchase #6	$95.45	8.732%	$103.7847	$103.78	$103.80	$103.80
Purchase #7	$78.45	6.529%	$83.572	$83.57	$83.55	$83.60
7 purchase totals =	$713.35		$784.1060	$784.09	$784.10	$784.20