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	$41.30	7.484%	$44.3909	$44.39	$44.40	$44.40
Purchase #2	$53.95	13.713%	$61.3482	$61.35	$61.35	$61.30
Purchase #3	$11.83	4.152%	$12.3212	$12.32	$12.30	$12.30
Purchase #4	$73.89	12.134%	$82.8558	$82.86	$82.85	$82.90
Purchase #5	$31.82	10.387%	$35.1251	$35.13	$35.15	$35.10
Purchase #6	$178.89	4.700%	$187.2978	$187.30	$187.30	$187.30
Purchase #7	$166.68	11.126%	$185.2248	$185.22	$185.20	$185.20
7 purchase totals =	$558.36		$608.5638	$608.57	$608.55	$608.50