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	$78.29	8.733%	$85.1271	$85.13	$85.15	$85.10
Purchase #2	$156.79	5.377%	$165.2206	$165.22	$165.20	$165.20
Purchase #3	$193.59	11.539%	$215.9284	$215.93	$215.95	$215.90
Purchase #4	$223.38	11.345%	$248.7225	$248.72	$248.70	$248.70
Purchase #5	$146.74	12.151%	$164.5704	$164.57	$164.55	$164.60
Purchase #6	$149.25	12.467%	$167.857	$167.86	$167.85	$167.90
Purchase #7	$153.63	5.729%	$162.4315	$162.43	$162.45	$162.40
7 purchase totals =	$1,101.67		$1,209.8575	$1,209.86	$1,209.85	$1,209.80