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	$214.80	9.573%	$235.3628	$235.36	$235.35	$235.40
Purchase #2	$71.53	9.259%	$78.153	$78.15	$78.15	$78.20
Purchase #3	$96.61	10.347%	$106.6062	$106.61	$106.60	$106.60
Purchase #4	$114.35	6.277%	$121.5277	$121.53	$121.55	$121.50
Purchase #5	$19.97	7.546%	$21.4769	$21.48	$21.50	$21.50
Purchase #6	$221.82	13.467%	$251.6925	$251.69	$251.70	$251.70
Purchase #7	$173.75	13.331%	$196.9126	$196.91	$196.90	$196.90
7 purchase totals =	$912.83		$1,011.7317	$1,011.73	$1,011.75	$1,011.80