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	$176.50	8.563%	$191.6137	$191.61	$191.60	$191.60
Purchase #2	$9.94	13.709%	$11.3027	$11.30	$11.30	$11.30
Purchase #3	$80.61	6.418%	$85.7835	$85.78	$85.80	$85.80
Purchase #4	$87.74	4.429%	$91.626	$91.63	$91.65	$91.60
Purchase #5	$142.65	6.432%	$151.8252	$151.83	$151.85	$151.80
Purchase #6	$200.80	9.476%	$219.8278	$219.83	$219.85	$219.80
Purchase #7	$130.72	4.729%	$136.9017	$136.90	$136.90	$136.90
7 purchase totals =	$828.96		$888.8806	$888.88	$888.95	$888.80