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	$162.72	11.275%	$181.0667	$181.07	$181.05	$181.10
Purchase #2	$145.27	5.344%	$153.0332	$153.03	$153.05	$153.00
Purchase #3	$171.90	4.354%	$179.3845	$179.38	$179.40	$179.40
Purchase #4	$209.40	10.595%	$231.5859	$231.59	$231.60	$231.60
Purchase #5	$126.25	4.113%	$131.4427	$131.44	$131.45	$131.40
Purchase #6	$207.37	8.661%	$225.3303	$225.33	$225.35	$225.30
Purchase #7	$62.79	13.650%	$71.3608	$71.36	$71.35	$71.40
7 purchase totals =	$1,085.70		$1,173.2041	$1,173.20	$1,173.25	$1,173.20