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	$138.53	9.620%	$151.8566	$151.86	$151.85	$151.90
Purchase #2	$232.54	4.715%	$243.5043	$243.50	$243.50	$243.50
Purchase #3	$23.96	13.739%	$27.2519	$27.25	$27.25	$27.30
Purchase #4	$242.76	7.542%	$261.069	$261.07	$261.05	$261.10
Purchase #5	$77.89	3.543%	$80.6496	$80.65	$80.65	$80.60
Purchase #6	$170.26	5.581%	$179.7622	$179.76	$179.75	$179.80
Purchase #7	$143.79	5.395%	$151.5475	$151.55	$151.55	$151.50
7 purchase totals =	$1,029.73		$1,095.6411	$1,095.64	$1,095.60	$1,095.70