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	$197.38	8.338%	$213.8375	$213.84	$213.85	$213.80
Purchase #2	$80.81	11.369%	$89.9973	$90.00	$90.00	$90.00
Purchase #3	$82.51	9.384%	$90.2527	$90.25	$90.25	$90.30
Purchase #4	$41.45	5.394%	$43.6858	$43.69	$43.70	$43.70
Purchase #5	$24.37	5.102%	$25.6134	$25.61	$25.60	$25.60
Purchase #6	$86.39	6.375%	$91.8974	$91.90	$91.90	$91.90
Purchase #7	$93.77	4.830%	$98.2991	$98.30	$98.30	$98.30
7 purchase totals =	$606.68		$653.5832	$653.59	$653.60	$653.60