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	$170.94	13.745%	$194.4357	$194.44	$194.45	$194.40
Purchase #2	$102.80	13.361%	$116.5351	$116.54	$116.55	$116.50
Purchase #3	$157.73	13.692%	$179.3264	$179.33	$179.35	$179.30
Purchase #4	$163.51	8.800%	$177.8989	$177.90	$177.90	$177.90
Purchase #5	$27.80	13.676%	$31.6019	$31.60	$31.60	$31.60
Purchase #6	$97.39	3.391%	$100.6925	$100.69	$100.70	$100.70
Purchase #7	$202.89	7.848%	$218.8128	$218.81	$218.80	$218.80
7 purchase totals =	$923.06		$1,019.3033	$1,019.31	$1,019.35	$1,019.20