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	$219.29	8.550%	$238.0393	$238.04	$238.05	$238.00
Purchase #2	$236.69	4.116%	$246.4322	$246.43	$246.45	$246.40
Purchase #3	$135.53	4.398%	$141.4906	$141.49	$141.50	$141.50
Purchase #4	$100.77	3.437%	$104.2335	$104.23	$104.25	$104.20
Purchase #5	$197.70	9.125%	$215.7401	$215.74	$215.75	$215.70
Purchase #6	$155.93	10.643%	$172.5256	$172.53	$172.55	$172.50
Purchase #7	$48.78	12.173%	$54.718	$54.72	$54.70	$54.70
7 purchase totals =	$1,094.69		$1,173.1793	$1,173.18	$1,173.25	$1,173.00