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	$59.86	9.448%	$65.5156	$65.52	$65.50	$65.50
Purchase #2	$196.40	13.874%	$223.6485	$223.65	$223.65	$223.60
Purchase #3	$209.30	9.685%	$229.5707	$229.57	$229.55	$229.60
Purchase #4	$142.68	5.185%	$150.078	$150.08	$150.10	$150.10
Purchase #5	$132.67	7.167%	$142.1785	$142.18	$142.20	$142.20
Purchase #6	$213.89	3.446%	$221.2606	$221.26	$221.25	$221.30
Purchase #7	$73.63	3.794%	$76.4235	$76.42	$76.40	$76.40
7 purchase totals =	$1,028.43		$1,108.6754	$1,108.68	$1,108.65	$1,108.70