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	$86.25	10.698%	$95.477	$95.48	$95.50	$95.50
Purchase #2	$161.44	8.364%	$174.9428	$174.94	$174.95	$174.90
Purchase #3	$173.50	12.575%	$195.3176	$195.32	$195.30	$195.30
Purchase #4	$68.64	5.751%	$72.5875	$72.59	$72.60	$72.60
Purchase #5	$91.53	10.197%	$100.8633	$100.86	$100.85	$100.90
Purchase #6	$134.69	11.724%	$150.4811	$150.48	$150.50	$150.50
Purchase #7	$216.60	13.378%	$245.5767	$245.58	$245.60	$245.60
7 purchase totals =	$932.65		$1,035.2460	$1,035.25	$1,035.30	$1,035.30