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	$148.50	10.862%	$164.6301	$164.63	$164.65	$164.60
Purchase #2	$44.84	3.387%	$46.3587	$46.36	$46.35	$46.40
Purchase #3	$182.63	7.553%	$196.424	$196.42	$196.40	$196.40
Purchase #4	$85.98	13.376%	$97.4807	$97.48	$97.50	$97.50
Purchase #5	$215.85	7.245%	$231.4883	$231.49	$231.50	$231.50
Purchase #6	$152.64	7.493%	$164.0773	$164.08	$164.10	$164.10
Purchase #7	$209.68	6.439%	$223.1813	$223.18	$223.20	$223.20
7 purchase totals =	$1,040.12		$1,123.6404	$1,123.64	$1,123.70	$1,123.70