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	$182.78	13.538%	$207.5248	$207.52	$207.50	$207.50
Purchase #2	$38.80	6.618%	$41.3678	$41.37	$41.35	$41.40
Purchase #3	$217.25	3.377%	$224.5865	$224.59	$224.60	$224.60
Purchase #4	$158.53	4.496%	$165.6575	$165.66	$165.65	$165.70
Purchase #5	$90.68	3.263%	$93.6389	$93.64	$93.65	$93.60
Purchase #6	$150.45	10.689%	$166.5316	$166.53	$166.55	$166.50
Purchase #7	$98.46	12.798%	$111.0609	$111.06	$111.05	$111.10
7 purchase totals =	$936.95		$1,010.3680	$1,010.37	$1,010.35	$1,010.40