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	$183.94	4.672%	$192.5337	$192.53	$192.55	$192.50
Purchase #2	$202.73	11.160%	$225.3547	$225.35	$225.35	$225.40
Purchase #3	$35.72	5.365%	$37.6364	$37.64	$37.65	$37.60
Purchase #4	$179.30	3.324%	$185.2599	$185.26	$185.25	$185.30
Purchase #5	$115.78	3.572%	$119.9157	$119.92	$119.90	$119.90
Purchase #6	$113.94	9.590%	$124.8668	$124.87	$124.85	$124.90
Purchase #7	$237.86	8.812%	$258.8202	$258.82	$258.80	$258.80
7 purchase totals =	$1,069.27		$1,144.3874	$1,144.39	$1,144.35	$1,144.40