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	$171.42	6.520%	$182.5966	$182.60	$182.60	$182.60
Purchase #2	$8.79	12.443%	$9.8837	$9.88	$9.90	$9.90
Purchase #3	$225.78	7.270%	$242.1942	$242.19	$242.20	$242.20
Purchase #4	$35.27	12.288%	$39.604	$39.60	$39.60	$39.60
Purchase #5	$72.90	5.799%	$77.1275	$77.13	$77.15	$77.10
Purchase #6	$235.92	7.723%	$254.1401	$254.14	$254.15	$254.10
Purchase #7	$190.37	10.565%	$210.4826	$210.48	$210.50	$210.50
7 purchase totals =	$940.45		$1,016.0287	$1,016.02	$1,016.10	$1,016.00