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	$131.93	11.580%	$147.2075	$147.21	$147.20	$147.20
Purchase #2	$6.57	11.839%	$7.3478	$7.35	$7.35	$7.30
Purchase #3	$57.70	12.504%	$64.9148	$64.91	$64.90	$64.90
Purchase #4	$138.32	13.442%	$156.913	$156.91	$156.90	$156.90
Purchase #5	$19.92	8.245%	$21.5624	$21.56	$21.55	$21.60
Purchase #6	$51.50	5.853%	$54.5143	$54.51	$54.50	$54.50
Purchase #7	$160.51	7.569%	$172.659	$172.66	$172.65	$172.70
7 purchase totals =	$566.45		$625.1188	$625.11	$625.05	$625.10