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	$152.83	6.178%	$162.2718	$162.27	$162.25	$162.30
Purchase #2	$120.30	5.589%	$127.0236	$127.02	$127.00	$127.00
Purchase #3	$90.69	3.567%	$93.9249	$93.92	$93.90	$93.90
Purchase #4	$124.61	13.129%	$140.97	$140.97	$140.95	$141.00
Purchase #5	$34.45	9.140%	$37.5987	$37.60	$37.60	$37.60
Purchase #6	$192.60	6.636%	$205.3809	$205.38	$205.40	$205.40
Purchase #7	$244.26	3.320%	$252.3694	$252.37	$252.35	$252.40
7 purchase totals =	$959.74		$1,019.5393	$1,019.53	$1,019.45	$1,019.60