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	$203.83	11.551%	$227.3744	$227.37	$227.35	$227.40
Purchase #2	$91.73	12.760%	$103.4347	$103.43	$103.45	$103.40
Purchase #3	$184.45	3.763%	$191.3909	$191.39	$191.40	$191.40
Purchase #4	$79.40	9.122%	$86.6429	$86.64	$86.65	$86.60
Purchase #5	$126.85	11.659%	$141.6394	$141.64	$141.65	$141.60
Purchase #6	$166.92	13.405%	$189.2956	$189.30	$189.30	$189.30
Purchase #7	$180.99	13.421%	$205.2807	$205.28	$205.30	$205.30
7 purchase totals =	$1,034.17		$1,145.0586	$1,145.05	$1,145.10	$1,145.00