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	$162.53	3.102%	$167.5717	$167.57	$167.55	$167.60
Purchase #2	$99.55	11.639%	$111.1366	$111.14	$111.15	$111.10
Purchase #3	$188.94	5.620%	$199.5584	$199.56	$199.55	$199.60
Purchase #4	$99.63	8.381%	$107.98	$107.98	$108.00	$108.00
Purchase #5	$172.41	7.386%	$185.1442	$185.14	$185.15	$185.10
Purchase #6	$213.96	12.674%	$241.0773	$241.08	$241.10	$241.10
Purchase #7	$196.41	12.378%	$220.7216	$220.72	$220.70	$220.70
7 purchase totals =	$1,133.43		$1,233.1898	$1,233.19	$1,233.20	$1,233.20