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	$65.47	10.825%	$72.5571	$72.56	$72.55	$72.60
Purchase #2	$242.91	3.683%	$251.8564	$251.86	$251.85	$251.90
Purchase #3	$174.88	6.139%	$185.6159	$185.62	$185.60	$185.60
Purchase #4	$200.75	10.158%	$221.1422	$221.14	$221.15	$221.10
Purchase #5	$95.78	12.828%	$108.0667	$108.07	$108.05	$108.10
Purchase #6	$157.34	11.361%	$175.2154	$175.22	$175.20	$175.20
Purchase #7	$213.97	4.672%	$223.9667	$223.97	$223.95	$224.00
7 purchase totals =	$1,151.10		$1,238.4204	$1,238.44	$1,238.35	$1,238.50