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	$233.25	12.344%	$262.0424	$262.04	$262.05	$262.00
Purchase #2	$237.98	3.747%	$246.8971	$246.90	$246.90	$246.90
Purchase #3	$102.27	3.306%	$105.651	$105.65	$105.65	$105.70
Purchase #4	$120.50	13.747%	$137.0651	$137.07	$137.05	$137.10
Purchase #5	$72.81	12.797%	$82.1275	$82.13	$82.15	$82.10
Purchase #6	$144.91	13.730%	$164.8061	$164.81	$164.80	$164.80
Purchase #7	$64.78	12.325%	$72.7641	$72.76	$72.75	$72.80
7 purchase totals =	$976.50		$1,071.3533	$1,071.36	$1,071.35	$1,071.40