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	$83.62	13.826%	$95.1813	$95.18	$95.20	$95.20
Purchase #2	$13.67	8.529%	$14.8359	$14.84	$14.85	$14.80
Purchase #3	$30.82	5.243%	$32.4359	$32.44	$32.45	$32.40
Purchase #4	$38.93	9.272%	$42.5396	$42.54	$42.55	$42.50
Purchase #5	$93.36	5.359%	$98.3632	$98.36	$98.35	$98.40
Purchase #6	$106.41	9.548%	$116.57	$116.57	$116.55	$116.60
Purchase #7	$40.28	7.490%	$43.297	$43.30	$43.30	$43.30
7 purchase totals =	$407.09		$443.2229	$443.23	$443.25	$443.20