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	$82.63	5.535%	$87.2036	$87.20	$87.20	$87.20
Purchase #2	$201.57	3.648%	$208.9233	$208.92	$208.90	$208.90
Purchase #3	$88.75	9.198%	$96.9132	$96.91	$96.90	$96.90
Purchase #4	$144.76	7.241%	$155.2421	$155.24	$155.25	$155.20
Purchase #5	$183.47	7.282%	$196.8303	$196.83	$196.85	$196.80
Purchase #6	$141.47	9.440%	$154.8248	$154.82	$154.80	$154.80
Purchase #7	$151.98	13.740%	$172.8621	$172.86	$172.85	$172.90
7 purchase totals =	$994.63		$1,072.7994	$1,072.78	$1,072.75	$1,072.70