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	$184.98	7.835%	$199.4732	$199.47	$199.45	$199.50
Purchase #2	$111.56	6.447%	$118.7523	$118.75	$118.75	$118.80
Purchase #3	$183.50	8.702%	$199.4682	$199.47	$199.45	$199.50
Purchase #4	$192.61	10.840%	$213.4889	$213.49	$213.50	$213.50
Purchase #5	$176.82	7.465%	$190.0196	$190.02	$190.00	$190.00
Purchase #6	$19.96	13.761%	$22.7067	$22.71	$22.70	$22.70
Purchase #7	$109.43	8.270%	$118.4799	$118.48	$118.50	$118.50
7 purchase totals =	$978.86		$1,062.3888	$1,062.39	$1,062.35	$1,062.50