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	$100.83	11.440%	$112.365	$112.37	$112.35	$112.40
Purchase #2	$44.75	9.124%	$48.833	$48.83	$48.85	$48.80
Purchase #3	$248.76	10.510%	$274.9047	$274.90	$274.90	$274.90
Purchase #4	$162.40	3.675%	$168.3682	$168.37	$168.35	$168.40
Purchase #5	$78.60	5.591%	$82.9945	$82.99	$83.00	$83.00
Purchase #6	$181.26	10.759%	$200.7618	$200.76	$200.75	$200.80
Purchase #7	$245.56	9.141%	$268.0066	$268.01	$268.00	$268.00
7 purchase totals =	$1,062.16		$1,156.2338	$1,156.23	$1,156.20	$1,156.30