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	$193.26	9.539%	$211.6951	$211.70	$211.70	$211.70
Purchase #2	$234.63	9.277%	$256.3966	$256.40	$256.40	$256.40
Purchase #3	$200.69	8.397%	$217.5419	$217.54	$217.55	$217.50
Purchase #4	$125.35	12.106%	$140.5249	$140.52	$140.50	$140.50
Purchase #5	$95.51	3.171%	$98.5386	$98.54	$98.55	$98.50
Purchase #6	$30.36	3.848%	$31.5283	$31.53	$31.55	$31.50
Purchase #7	$117.92	8.337%	$127.751	$127.75	$127.75	$127.80
7 purchase totals =	$997.72		$1,083.9764	$1,083.98	$1,084.00	$1,083.90