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	$36.49	3.343%	$37.7099	$37.71	$37.70	$37.70
Purchase #2	$12.66	4.803%	$13.2681	$13.27	$13.25	$13.30
Purchase #3	$50.86	10.834%	$56.3702	$56.37	$56.35	$56.40
Purchase #4	$14.39	12.697%	$16.2171	$16.22	$16.20	$16.20
Purchase #5	$81.89	6.493%	$87.2071	$87.21	$87.20	$87.20
Purchase #6	$182.75	7.518%	$196.4891	$196.49	$196.50	$196.50
Purchase #7	$53.33	4.271%	$55.6077	$55.61	$55.60	$55.60
7 purchase totals =	$432.37		$462.8692	$462.88	$462.80	$462.90