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	$88.44	11.464%	$98.5788	$98.58	$98.60	$98.60
Purchase #2	$196.97	5.829%	$208.4514	$208.45	$208.45	$208.50
Purchase #3	$102.45	9.613%	$112.2985	$112.30	$112.30	$112.30
Purchase #4	$233.41	13.665%	$265.3055	$265.31	$265.30	$265.30
Purchase #5	$90.34	5.216%	$95.0521	$95.05	$95.05	$95.10
Purchase #6	$248.52	5.810%	$262.959	$262.96	$262.95	$263.00
Purchase #7	$141.65	8.483%	$153.6662	$153.67	$153.65	$153.70
7 purchase totals =	$1,101.78		$1,196.3115	$1,196.32	$1,196.30	$1,196.50