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	$212.54	3.393%	$219.7515	$219.75	$219.75	$219.80
Purchase #2	$126.32	3.430%	$130.6528	$130.65	$130.65	$130.70
Purchase #3	$196.38	7.371%	$210.8552	$210.86	$210.85	$210.90
Purchase #4	$67.81	6.136%	$71.9708	$71.97	$71.95	$72.00
Purchase #5	$23.53	9.232%	$25.7023	$25.70	$25.70	$25.70
Purchase #6	$199.47	11.680%	$222.7681	$222.77	$222.75	$222.80
Purchase #7	$145.60	12.810%	$164.2514	$164.25	$164.25	$164.30
7 purchase totals =	$971.65		$1,045.9521	$1,045.95	$1,045.90	$1,046.20