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	$224.98	4.796%	$235.77	$235.77	$235.75	$235.80
Purchase #2	$33.97	9.269%	$37.1187	$37.12	$37.10	$37.10
Purchase #3	$212.61	12.370%	$238.9099	$238.91	$238.90	$238.90
Purchase #4	$171.95	4.723%	$180.0712	$180.07	$180.05	$180.10
Purchase #5	$226.68	5.224%	$238.5218	$238.52	$238.50	$238.50
Purchase #6	$212.40	5.208%	$223.4618	$223.46	$223.45	$223.50
Purchase #7	$14.30	5.514%	$15.0885	$15.09	$15.10	$15.10
7 purchase totals =	$1,096.89		$1,168.9419	$1,168.94	$1,168.85	$1,169.00