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	$235.96	11.241%	$262.4843	$262.48	$262.50	$262.50
Purchase #2	$82.78	9.668%	$90.7832	$90.78	$90.80	$90.80
Purchase #3	$7.83	6.750%	$8.3585	$8.36	$8.35	$8.40
Purchase #4	$233.86	6.353%	$248.7171	$248.72	$248.70	$248.70
Purchase #5	$152.80	4.307%	$159.3811	$159.38	$159.40	$159.40
Purchase #6	$197.60	7.801%	$213.0148	$213.01	$213.00	$213.00
Purchase #7	$39.91	6.770%	$42.6119	$42.61	$42.60	$42.60
7 purchase totals =	$950.74		$1,025.3509	$1,025.34	$1,025.35	$1,025.40