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	$239.96	9.619%	$263.0418	$263.04	$263.05	$263.00
Purchase #2	$158.69	7.818%	$171.0964	$171.10	$171.10	$171.10
Purchase #3	$90.64	11.305%	$100.8869	$100.89	$100.90	$100.90
Purchase #4	$241.83	11.481%	$269.5945	$269.59	$269.60	$269.60
Purchase #5	$153.58	6.290%	$163.2402	$163.24	$163.25	$163.20
Purchase #6	$68.63	4.735%	$71.8796	$71.88	$71.90	$71.90
Purchase #7	$131.75	7.487%	$141.6141	$141.61	$141.60	$141.60
7 purchase totals =	$1,085.08		$1,181.3535	$1,181.35	$1,181.40	$1,181.30