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	$172.61	11.419%	$192.3203	$192.32	$192.30	$192.30
Purchase #2	$67.65	13.423%	$76.7307	$76.73	$76.75	$76.70
Purchase #3	$136.49	10.830%	$151.2719	$151.27	$151.25	$151.30
Purchase #4	$211.66	4.305%	$220.772	$220.77	$220.75	$220.80
Purchase #5	$178.75	6.599%	$190.5457	$190.55	$190.55	$190.50
Purchase #6	$73.32	4.558%	$76.6619	$76.66	$76.65	$76.70
Purchase #7	$190.62	3.169%	$196.6607	$196.66	$196.65	$196.70
7 purchase totals =	$1,031.10		$1,104.9632	$1,104.96	$1,104.90	$1,105.00