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	$201.47	3.409%	$208.3381	$208.34	$208.35	$208.30
Purchase #2	$39.61	5.565%	$41.8143	$41.81	$41.80	$41.80
Purchase #3	$164.89	8.781%	$179.369	$179.37	$179.35	$179.40
Purchase #4	$219.76	6.458%	$233.9521	$233.95	$233.95	$234.00
Purchase #5	$168.37	6.241%	$178.878	$178.88	$178.90	$178.90
Purchase #6	$182.34	6.434%	$194.0718	$194.07	$194.05	$194.10
Purchase #7	$59.85	12.577%	$67.3773	$67.38	$67.40	$67.40
7 purchase totals =	$1,036.29		$1,103.8006	$1,103.80	$1,103.80	$1,103.90