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	$207.30	7.401%	$222.6423	$222.64	$222.65	$222.60
Purchase #2	$9.50	5.285%	$10.0021	$10.00	$10.00	$10.00
Purchase #3	$92.29	6.819%	$98.5833	$98.58	$98.60	$98.60
Purchase #4	$207.94	8.103%	$224.7894	$224.79	$224.80	$224.80
Purchase #5	$82.90	3.558%	$85.8496	$85.85	$85.85	$85.80
Purchase #6	$158.32	11.425%	$176.4081	$176.41	$176.40	$176.40
Purchase #7	$209.34	6.307%	$222.5431	$222.54	$222.55	$222.50
7 purchase totals =	$967.59		$1,040.8179	$1,040.81	$1,040.85	$1,040.70