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	$106.31	4.220%	$110.7963	$110.80	$110.80	$110.80
Purchase #2	$99.37	4.725%	$104.0652	$104.07	$104.05	$104.10
Purchase #3	$44.59	4.482%	$46.5885	$46.59	$46.60	$46.60
Purchase #4	$208.75	4.846%	$218.866	$218.87	$218.85	$218.90
Purchase #5	$206.39	5.371%	$217.4752	$217.48	$217.50	$217.50
Purchase #6	$178.30	10.333%	$196.7237	$196.72	$196.70	$196.70
Purchase #7	$208.69	4.476%	$218.031	$218.03	$218.05	$218.00
7 purchase totals =	$1,052.40		$1,112.5459	$1,112.56	$1,112.55	$1,112.60