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	$186.63	5.540%	$196.9693	$196.97	$196.95	$197.00
Purchase #2	$171.86	7.462%	$184.6842	$184.68	$184.70	$184.70
Purchase #3	$189.97	10.182%	$209.3127	$209.31	$209.30	$209.30
Purchase #4	$89.77	9.547%	$98.3403	$98.34	$98.35	$98.30
Purchase #5	$85.67	8.296%	$92.7772	$92.78	$92.80	$92.80
Purchase #6	$140.89	6.628%	$150.2282	$150.23	$150.25	$150.20
Purchase #7	$150.49	3.417%	$155.6322	$155.63	$155.65	$155.60
7 purchase totals =	$1,015.28		$1,087.9441	$1,087.94	$1,088.00	$1,087.90