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	$148.25	5.665%	$156.6484	$156.65	$156.65	$156.60
Purchase #2	$139.37	3.601%	$144.3887	$144.39	$144.40	$144.40
Purchase #3	$196.29	7.630%	$211.2669	$211.27	$211.25	$211.30
Purchase #4	$176.86	4.468%	$184.7621	$184.76	$184.75	$184.80
Purchase #5	$9.43	13.862%	$10.7372	$10.74	$10.75	$10.70
Purchase #6	$232.27	12.725%	$261.8264	$261.83	$261.85	$261.80
Purchase #7	$109.27	7.525%	$117.4926	$117.49	$117.50	$117.50
7 purchase totals =	$1,011.74		$1,087.1223	$1,087.13	$1,087.15	$1,087.10