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	$197.69	7.180%	$211.8841	$211.88	$211.90	$211.90
Purchase #2	$168.88	5.694%	$178.496	$178.50	$178.50	$178.50
Purchase #3	$14.27	7.308%	$15.3129	$15.31	$15.30	$15.30
Purchase #4	$142.92	10.863%	$158.4454	$158.45	$158.45	$158.40
Purchase #5	$144.37	11.397%	$160.8238	$160.82	$160.80	$160.80
Purchase #6	$196.48	12.831%	$221.6903	$221.69	$221.70	$221.70
Purchase #7	$14.86	3.342%	$15.3566	$15.36	$15.35	$15.40
7 purchase totals =	$879.47		$962.0091	$962.01	$962.00	$962.00