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	$222.86	9.696%	$244.4685	$244.47	$244.45	$244.50
Purchase #2	$25.83	5.669%	$27.2943	$27.29	$27.30	$27.30
Purchase #3	$168.99	4.151%	$176.0048	$176.00	$176.00	$176.00
Purchase #4	$94.89	11.140%	$105.4607	$105.46	$105.45	$105.50
Purchase #5	$212.42	4.347%	$221.6539	$221.65	$221.65	$221.70
Purchase #6	$156.97	13.575%	$178.2787	$178.28	$178.30	$178.30
Purchase #7	$101.32	11.208%	$112.6759	$112.68	$112.70	$112.70
7 purchase totals =	$983.28		$1,065.8368	$1,065.83	$1,065.85	$1,066.00