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	$200.35	5.211%	$210.7902	$210.79	$210.80	$210.80
Purchase #2	$11.58	13.376%	$13.1289	$13.13	$13.15	$13.10
Purchase #3	$162.45	3.595%	$168.2901	$168.29	$168.30	$168.30
Purchase #4	$248.49	4.223%	$258.9837	$258.98	$259.00	$259.00
Purchase #5	$150.60	12.589%	$169.559	$169.56	$169.55	$169.60
Purchase #6	$111.61	3.227%	$115.2117	$115.21	$115.20	$115.20
Purchase #7	$75.56	3.768%	$78.4071	$78.41	$78.40	$78.40
7 purchase totals =	$960.64		$1,014.3707	$1,014.37	$1,014.40	$1,014.40