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	$96.93	11.485%	$108.0624	$108.06	$108.05	$108.10
Purchase #2	$199.55	10.476%	$220.4549	$220.45	$220.45	$220.50
Purchase #3	$14.61	8.778%	$15.8925	$15.89	$15.90	$15.90
Purchase #4	$219.98	5.124%	$231.2518	$231.25	$231.25	$231.30
Purchase #5	$110.86	11.438%	$123.5402	$123.54	$123.55	$123.50
Purchase #6	$163.53	13.485%	$185.582	$185.58	$185.60	$185.60
Purchase #7	$144.78	13.643%	$164.5323	$164.53	$164.55	$164.50
7 purchase totals =	$950.24		$1,049.3161	$1,049.30	$1,049.35	$1,049.40