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	$105.36	8.145%	$113.9416	$113.94	$113.95	$113.90
Purchase #2	$144.72	13.403%	$164.1168	$164.12	$164.10	$164.10
Purchase #3	$144.43	7.508%	$155.2738	$155.27	$155.25	$155.30
Purchase #4	$113.84	11.156%	$126.54	$126.54	$126.55	$126.50
Purchase #5	$198.59	6.423%	$211.3454	$211.35	$211.35	$211.30
Purchase #6	$131.40	8.303%	$142.3101	$142.31	$142.30	$142.30
Purchase #7	$178.35	10.256%	$196.6416	$196.64	$196.65	$196.60
7 purchase totals =	$1,016.69		$1,110.1693	$1,110.17	$1,110.15	$1,110.00