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	$202.69	9.367%	$221.676	$221.68	$221.70	$221.70
Purchase #2	$18.95	7.183%	$20.3112	$20.31	$20.30	$20.30
Purchase #3	$202.77	7.630%	$218.2414	$218.24	$218.25	$218.20
Purchase #4	$38.50	7.648%	$41.4445	$41.44	$41.45	$41.40
Purchase #5	$211.82	6.665%	$225.9378	$225.94	$225.95	$225.90
Purchase #6	$38.79	4.346%	$40.4758	$40.48	$40.50	$40.50
Purchase #7	$228.29	7.543%	$245.5099	$245.51	$245.50	$245.50
7 purchase totals =	$941.81		$1,013.5966	$1,013.60	$1,013.65	$1,013.50