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	$222.98	13.632%	$253.3766	$253.38	$253.40	$253.40
Purchase #2	$244.26	10.149%	$269.0499	$269.05	$269.05	$269.00
Purchase #3	$68.59	3.874%	$71.2472	$71.25	$71.25	$71.20
Purchase #4	$48.81	13.807%	$55.5492	$55.55	$55.55	$55.50
Purchase #5	$213.93	10.352%	$236.076	$236.08	$236.10	$236.10
Purchase #6	$164.45	12.510%	$185.0227	$185.02	$185.00	$185.00
Purchase #7	$24.39	5.759%	$25.7946	$25.79	$25.80	$25.80
7 purchase totals =	$987.41		$1,096.1162	$1,096.12	$1,096.15	$1,096.00