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	$197.51	11.236%	$219.7022	$219.70	$219.70	$219.70
Purchase #2	$79.32	5.296%	$83.5208	$83.52	$83.50	$83.50
Purchase #3	$201.59	10.517%	$222.7912	$222.79	$222.80	$222.80
Purchase #4	$12.47	12.468%	$14.0248	$14.02	$14.00	$14.00
Purchase #5	$47.88	10.227%	$52.7767	$52.78	$52.80	$52.80
Purchase #6	$168.67	10.721%	$186.7531	$186.75	$186.75	$186.80
Purchase #7	$6.87	7.256%	$7.3685	$7.37	$7.35	$7.40
7 purchase totals =	$714.31		$786.9373	$786.93	$786.90	$787.00