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	$192.61	11.272%	$214.321	$214.32	$214.30	$214.30
Purchase #2	$205.26	8.427%	$222.5573	$222.56	$222.55	$222.60
Purchase #3	$13.43	10.655%	$14.861	$14.86	$14.85	$14.90
Purchase #4	$9.44	9.144%	$10.3032	$10.30	$10.30	$10.30
Purchase #5	$211.97	4.870%	$222.2929	$222.29	$222.30	$222.30
Purchase #6	$69.86	12.107%	$78.318	$78.32	$78.30	$78.30
Purchase #7	$127.39	6.495%	$135.664	$135.66	$135.65	$135.70
7 purchase totals =	$829.96		$898.3174	$898.31	$898.25	$898.40