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	$13.43	5.186%	$14.1265	$14.13	$14.15	$14.10
Purchase #2	$143.82	4.698%	$150.5767	$150.58	$150.60	$150.60
Purchase #3	$65.93	6.472%	$70.197	$70.20	$70.20	$70.20
Purchase #4	$244.54	5.191%	$257.2341	$257.23	$257.25	$257.20
Purchase #5	$210.96	3.296%	$217.9132	$217.91	$217.90	$217.90
Purchase #6	$242.54	13.348%	$274.9142	$274.91	$274.90	$274.90
Purchase #7	$187.73	4.645%	$196.4501	$196.45	$196.45	$196.50
7 purchase totals =	$1,108.95		$1,181.4118	$1,181.41	$1,181.45	$1,181.40