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	$196.58	9.600%	$215.4517	$215.45	$215.45	$215.50
Purchase #2	$39.84	6.628%	$42.4806	$42.48	$42.50	$42.50
Purchase #3	$149.70	4.326%	$156.176	$156.18	$156.20	$156.20
Purchase #4	$153.72	9.354%	$168.099	$168.10	$168.10	$168.10
Purchase #5	$210.25	4.693%	$220.117	$220.12	$220.10	$220.10
Purchase #6	$112.37	3.141%	$115.8995	$115.90	$115.90	$115.90
Purchase #7	$159.83	5.494%	$168.6111	$168.61	$168.60	$168.60
7 purchase totals =	$1,022.29		$1,086.8349	$1,086.84	$1,086.85	$1,086.90