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	$81.75	4.764%	$85.6446	$85.64	$85.65	$85.60
Purchase #2	$145.34	13.865%	$165.4914	$165.49	$165.50	$165.50
Purchase #3	$47.58	7.578%	$51.1856	$51.19	$51.20	$51.20
Purchase #4	$134.83	12.270%	$151.3736	$151.37	$151.35	$151.40
Purchase #5	$78.97	5.164%	$83.048	$83.05	$83.05	$83.00
Purchase #6	$52.74	5.441%	$55.6096	$55.61	$55.60	$55.60
Purchase #7	$169.95	13.323%	$192.5924	$192.59	$192.60	$192.60
7 purchase totals =	$711.16		$784.9452	$784.94	$784.95	$784.90