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	$181.62	8.389%	$196.8561	$196.86	$196.85	$196.90
Purchase #2	$160.51	6.761%	$171.3621	$171.36	$171.35	$171.40
Purchase #3	$191.80	4.576%	$200.5768	$200.58	$200.60	$200.60
Purchase #4	$30.71	8.477%	$33.3133	$33.31	$33.30	$33.30
Purchase #5	$170.93	12.863%	$192.9167	$192.92	$192.90	$192.90
Purchase #6	$10.30	4.219%	$10.7346	$10.73	$10.75	$10.70
Purchase #7	$210.52	6.677%	$224.5764	$224.58	$224.60	$224.60
7 purchase totals =	$956.39		$1,030.3360	$1,030.34	$1,030.35	$1,030.40