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	$247.84	4.611%	$259.2679	$259.27	$259.25	$259.30
Purchase #2	$195.82	8.835%	$213.1207	$213.12	$213.10	$213.10
Purchase #3	$50.95	3.566%	$52.7669	$52.77	$52.75	$52.80
Purchase #4	$171.60	11.260%	$190.9222	$190.92	$190.90	$190.90
Purchase #5	$70.48	11.663%	$78.7001	$78.70	$78.70	$78.70
Purchase #6	$66.29	10.277%	$73.1026	$73.10	$73.10	$73.10
Purchase #7	$195.36	6.534%	$208.1248	$208.12	$208.10	$208.10
7 purchase totals =	$998.34		$1,076.0052	$1,076.00	$1,075.90	$1,076.00