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	$213.70	4.152%	$222.5728	$222.57	$222.55	$222.60
Purchase #2	$63.56	9.330%	$69.4901	$69.49	$69.50	$69.50
Purchase #3	$208.33	7.307%	$223.5527	$223.55	$223.55	$223.60
Purchase #4	$238.31	11.508%	$265.7347	$265.73	$265.75	$265.70
Purchase #5	$111.44	10.369%	$122.9952	$123.00	$123.00	$123.00
Purchase #6	$128.94	10.175%	$142.0596	$142.06	$142.05	$142.10
Purchase #7	$60.65	4.620%	$63.452	$63.45	$63.45	$63.50
7 purchase totals =	$1,024.93		$1,109.8571	$1,109.85	$1,109.85	$1,110.00