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	$85.37	10.335%	$94.193	$94.19	$94.20	$94.20
Purchase #2	$29.31	9.732%	$32.1624	$32.16	$32.15	$32.20
Purchase #3	$227.92	6.426%	$242.5661	$242.57	$242.55	$242.60
Purchase #4	$90.76	13.813%	$103.2967	$103.30	$103.30	$103.30
Purchase #5	$185.33	7.838%	$199.8562	$199.86	$199.85	$199.90
Purchase #6	$220.94	9.444%	$241.8056	$241.81	$241.80	$241.80
Purchase #7	$65.96	9.194%	$72.0244	$72.02	$72.00	$72.00
7 purchase totals =	$905.59		$985.9044	$985.91	$985.85	$986.00