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	$167.64	9.495%	$183.5574	$183.56	$183.55	$183.60
Purchase #2	$194.40	10.526%	$214.8625	$214.86	$214.85	$214.90
Purchase #3	$101.83	3.237%	$105.1262	$105.13	$105.15	$105.10
Purchase #4	$138.43	8.638%	$150.3876	$150.39	$150.40	$150.40
Purchase #5	$106.39	7.784%	$114.6714	$114.67	$114.65	$114.70
Purchase #6	$194.31	10.630%	$214.9652	$214.97	$214.95	$215.00
Purchase #7	$68.95	13.280%	$78.1066	$78.11	$78.10	$78.10
7 purchase totals =	$971.95		$1,061.6769	$1,061.69	$1,061.65	$1,061.80