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	$208.72	5.133%	$219.4336	$219.43	$219.45	$219.40
Purchase #2	$213.57	11.806%	$238.7841	$238.78	$238.80	$238.80
Purchase #3	$11.56	5.729%	$12.2223	$12.22	$12.20	$12.20
Purchase #4	$171.53	11.408%	$191.0981	$191.10	$191.10	$191.10
Purchase #5	$124.52	12.297%	$139.8322	$139.83	$139.85	$139.80
Purchase #6	$136.41	6.206%	$144.8756	$144.88	$144.90	$144.90
Purchase #7	$62.99	8.483%	$68.3334	$68.33	$68.35	$68.30
7 purchase totals =	$929.30		$1,014.5793	$1,014.57	$1,014.65	$1,014.50