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	$203.35	4.727%	$212.9624	$212.96	$212.95	$213.00
Purchase #2	$164.82	3.808%	$171.0963	$171.10	$171.10	$171.10
Purchase #3	$46.60	12.255%	$52.3108	$52.31	$52.30	$52.30
Purchase #4	$45.45	13.804%	$51.7239	$51.72	$51.70	$51.70
Purchase #5	$190.89	7.453%	$205.117	$205.12	$205.10	$205.10
Purchase #6	$171.43	5.632%	$181.0849	$181.08	$181.10	$181.10
Purchase #7	$180.31	6.134%	$191.3702	$191.37	$191.35	$191.40
7 purchase totals =	$1,002.85		$1,065.6655	$1,065.66	$1,065.60	$1,065.70