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	$187.75	5.848%	$198.7296	$198.73	$198.75	$198.70
Purchase #2	$109.34	4.226%	$113.9607	$113.96	$113.95	$114.00
Purchase #3	$235.74	3.606%	$244.2408	$244.24	$244.25	$244.20
Purchase #4	$66.45	10.195%	$73.2246	$73.22	$73.20	$73.20
Purchase #5	$188.57	4.383%	$196.835	$196.84	$196.85	$196.80
Purchase #6	$66.48	8.409%	$72.0703	$72.07	$72.05	$72.10
Purchase #7	$144.52	13.849%	$164.5346	$164.53	$164.55	$164.50
7 purchase totals =	$998.85		$1,063.5956	$1,063.59	$1,063.60	$1,063.50