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	$196.33	12.698%	$221.26	$221.26	$221.25	$221.30
Purchase #2	$207.83	4.381%	$216.935	$216.94	$216.95	$216.90
Purchase #3	$164.90	4.310%	$172.0072	$172.01	$172.00	$172.00
Purchase #4	$55.55	8.755%	$60.4134	$60.41	$60.40	$60.40
Purchase #5	$158.59	3.443%	$164.0503	$164.05	$164.05	$164.10
Purchase #6	$167.25	9.642%	$183.3762	$183.38	$183.40	$183.40
Purchase #7	$48.55	3.699%	$50.3459	$50.35	$50.35	$50.30
7 purchase totals =	$999.00		$1,068.3880	$1,068.40	$1,068.40	$1,068.40