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	$101.34	7.643%	$109.0854	$109.09	$109.10	$109.10
Purchase #2	$144.34	4.739%	$151.1803	$151.18	$151.20	$151.20
Purchase #3	$203.46	5.785%	$215.2302	$215.23	$215.25	$215.20
Purchase #4	$236.32	8.264%	$255.8495	$255.85	$255.85	$255.80
Purchase #5	$125.69	3.653%	$130.2815	$130.28	$130.30	$130.30
Purchase #6	$143.76	9.351%	$157.203	$157.20	$157.20	$157.20
Purchase #7	$42.94	6.174%	$45.5911	$45.59	$45.60	$45.60
7 purchase totals =	$997.85		$1,064.4210	$1,064.42	$1,064.50	$1,064.40