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	$181.29	10.506%	$200.3363	$200.34	$200.35	$200.30
Purchase #2	$176.42	3.258%	$182.1678	$182.17	$182.15	$182.20
Purchase #3	$127.34	3.360%	$131.6186	$131.62	$131.60	$131.60
Purchase #4	$47.42	4.323%	$49.47	$49.47	$49.45	$49.50
Purchase #5	$13.98	12.569%	$15.7371	$15.74	$15.75	$15.70
Purchase #6	$208.79	13.661%	$237.3128	$237.31	$237.30	$237.30
Purchase #7	$236.29	11.664%	$263.8509	$263.85	$263.85	$263.90
7 purchase totals =	$991.53		$1,080.4935	$1,080.50	$1,080.45	$1,080.50