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	$189.61	11.770%	$211.9271	$211.93	$211.95	$211.90
Purchase #2	$117.85	11.588%	$131.5065	$131.51	$131.50	$131.50
Purchase #3	$126.43	4.568%	$132.2053	$132.21	$132.20	$132.20
Purchase #4	$193.38	13.381%	$219.2562	$219.26	$219.25	$219.30
Purchase #5	$136.54	11.237%	$151.883	$151.88	$151.90	$151.90
Purchase #6	$126.53	3.749%	$131.2736	$131.27	$131.25	$131.30
Purchase #7	$105.80	9.516%	$115.8679	$115.87	$115.85	$115.90
7 purchase totals =	$996.14		$1,093.9196	$1,093.93	$1,093.90	$1,094.00