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	$153.82	10.360%	$169.7558	$169.76	$169.75	$169.80
Purchase #2	$187.98	9.135%	$205.152	$205.15	$205.15	$205.20
Purchase #3	$215.48	12.584%	$242.596	$242.60	$242.60	$242.60
Purchase #4	$93.92	9.455%	$102.8001	$102.80	$102.80	$102.80
Purchase #5	$152.49	13.149%	$172.5409	$172.54	$172.55	$172.50
Purchase #6	$64.76	11.838%	$72.4263	$72.43	$72.45	$72.40
Purchase #7	$84.77	7.873%	$91.4439	$91.44	$91.45	$91.40
7 purchase totals =	$953.22		$1,056.7150	$1,056.72	$1,056.75	$1,056.70