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	$43.94	3.844%	$45.6291	$45.63	$45.65	$45.60
Purchase #2	$42.97	13.866%	$48.9282	$48.93	$48.95	$48.90
Purchase #3	$174.88	3.531%	$181.055	$181.06	$181.05	$181.10
Purchase #4	$200.75	6.381%	$213.5599	$213.56	$213.55	$213.60
Purchase #5	$232.29	7.455%	$249.6072	$249.61	$249.60	$249.60
Purchase #6	$67.59	7.867%	$72.9073	$72.91	$72.90	$72.90
Purchase #7	$198.36	10.235%	$218.6621	$218.66	$218.65	$218.70
7 purchase totals =	$960.78		$1,030.3488	$1,030.36	$1,030.35	$1,030.40