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	$196.83	9.678%	$215.8792	$215.88	$215.90	$215.90
Purchase #2	$89.68	12.141%	$100.568	$100.57	$100.55	$100.60
Purchase #3	$72.34	5.482%	$76.3057	$76.31	$76.30	$76.30
Purchase #4	$98.72	3.205%	$101.884	$101.88	$101.90	$101.90
Purchase #5	$238.38	4.182%	$248.3491	$248.35	$248.35	$248.30
Purchase #6	$54.38	7.691%	$58.5624	$58.56	$58.55	$58.60
Purchase #7	$197.60	3.464%	$204.4449	$204.44	$204.45	$204.40
7 purchase totals =	$947.93		$1,005.9933	$1,005.99	$1,006.00	$1,006.00