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	$179.31	9.655%	$196.6224	$196.62	$196.60	$196.60
Purchase #2	$125.94	9.731%	$138.1952	$138.20	$138.20	$138.20
Purchase #3	$102.36	13.656%	$116.3383	$116.34	$116.35	$116.30
Purchase #4	$246.51	3.620%	$255.4337	$255.43	$255.45	$255.40
Purchase #5	$142.59	9.561%	$156.223	$156.22	$156.20	$156.20
Purchase #6	$98.76	4.451%	$103.1558	$103.16	$103.15	$103.20
Purchase #7	$61.34	5.622%	$64.7885	$64.79	$64.80	$64.80
7 purchase totals =	$956.81		$1,030.7569	$1,030.76	$1,030.75	$1,030.70