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	$109.95	8.752%	$119.5728	$119.57	$119.55	$119.60
Purchase #2	$215.41	9.366%	$235.5853	$235.59	$235.60	$235.60
Purchase #3	$130.36	10.276%	$143.7558	$143.76	$143.75	$143.80
Purchase #4	$31.28	8.486%	$33.9344	$33.93	$33.95	$33.90
Purchase #5	$61.53	4.380%	$64.225	$64.23	$64.25	$64.20
Purchase #6	$139.62	7.680%	$150.3428	$150.34	$150.35	$150.30
Purchase #7	$249.67	8.779%	$271.5885	$271.59	$271.60	$271.60
7 purchase totals =	$937.82		$1,019.0046	$1,019.01	$1,019.05	$1,019.00