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	$174.42	12.691%	$196.5556	$196.56	$196.55	$196.60
Purchase #2	$241.98	5.561%	$255.4365	$255.44	$255.45	$255.40
Purchase #3	$132.82	10.233%	$146.4115	$146.41	$146.40	$146.40
Purchase #4	$89.94	4.676%	$94.1456	$94.15	$94.15	$94.10
Purchase #5	$81.96	5.378%	$86.3678	$86.37	$86.35	$86.40
Purchase #6	$113.62	5.166%	$119.4896	$119.49	$119.50	$119.50
Purchase #7	$188.25	13.325%	$213.3343	$213.33	$213.35	$213.30
7 purchase totals =	$1,022.99		$1,111.7409	$1,111.75	$1,111.75	$1,111.70