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	$157.26	10.655%	$174.0161	$174.02	$174.00	$174.00
Purchase #2	$97.36	13.549%	$110.5513	$110.55	$110.55	$110.60
Purchase #3	$75.74	3.741%	$78.5734	$78.57	$78.55	$78.60
Purchase #4	$138.52	11.677%	$154.695	$154.70	$154.70	$154.70
Purchase #5	$215.48	12.329%	$242.0465	$242.05	$242.05	$242.00
Purchase #6	$157.75	9.269%	$172.3718	$172.37	$172.35	$172.40
Purchase #7	$155.34	8.492%	$168.5315	$168.53	$168.55	$168.50
7 purchase totals =	$997.45		$1,100.7856	$1,100.79	$1,100.75	$1,100.80