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	$10.88	5.169%	$11.4424	$11.44	$11.45	$11.40
Purchase #2	$81.90	10.294%	$90.3308	$90.33	$90.35	$90.30
Purchase #3	$209.91	6.536%	$223.6297	$223.63	$223.65	$223.60
Purchase #4	$168.95	11.748%	$188.7982	$188.80	$188.80	$188.80
Purchase #5	$118.38	4.298%	$123.468	$123.47	$123.45	$123.50
Purchase #6	$200.91	11.828%	$224.6736	$224.67	$224.65	$224.70
Purchase #7	$207.92	5.354%	$219.052	$219.05	$219.05	$219.10
7 purchase totals =	$998.85		$1,081.3947	$1,081.39	$1,081.40	$1,081.40