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	$82.40	3.615%	$85.3788	$85.38	$85.40	$85.40
Purchase #2	$87.87	5.306%	$92.5324	$92.53	$92.55	$92.50
Purchase #3	$130.34	11.179%	$144.9107	$144.91	$144.90	$144.90
Purchase #4	$220.27	11.384%	$245.3455	$245.35	$245.35	$245.30
Purchase #5	$60.81	8.441%	$65.943	$65.94	$65.95	$65.90
Purchase #6	$192.66	11.538%	$214.8891	$214.89	$214.90	$214.90
Purchase #7	$202.98	12.374%	$228.0967	$228.10	$228.10	$228.10
7 purchase totals =	$977.33		$1,077.0962	$1,077.10	$1,077.15	$1,077.00