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	$175.27	13.670%	$199.2294	$199.23	$199.25	$199.20
Purchase #2	$171.30	11.779%	$191.4774	$191.48	$191.50	$191.50
Purchase #3	$158.71	12.751%	$178.9471	$178.95	$178.95	$178.90
Purchase #4	$23.71	6.673%	$25.2922	$25.29	$25.30	$25.30
Purchase #5	$226.43	12.874%	$255.5806	$255.58	$255.60	$255.60
Purchase #6	$13.40	10.620%	$14.8231	$14.82	$14.80	$14.80
Purchase #7	$158.61	10.694%	$175.5718	$175.57	$175.55	$175.60
7 purchase totals =	$927.43		$1,040.9216	$1,040.92	$1,040.95	$1,040.90