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	$211.63	10.389%	$233.6162	$233.62	$233.60	$233.60
Purchase #2	$39.88	7.330%	$42.8032	$42.80	$42.80	$42.80
Purchase #3	$66.91	6.868%	$71.5054	$71.51	$71.50	$71.50
Purchase #4	$130.79	10.760%	$144.863	$144.86	$144.85	$144.90
Purchase #5	$240.43	3.407%	$248.6215	$248.62	$248.60	$248.60
Purchase #6	$69.79	8.635%	$75.8164	$75.82	$75.80	$75.80
Purchase #7	$172.30	11.506%	$192.1248	$192.12	$192.10	$192.10
7 purchase totals =	$931.73		$1,009.3505	$1,009.35	$1,009.25	$1,009.30