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	$188.59	4.867%	$197.7687	$197.77	$197.75	$197.80
Purchase #2	$99.27	6.359%	$105.5826	$105.58	$105.60	$105.60
Purchase #3	$15.55	5.801%	$16.4521	$16.45	$16.45	$16.50
Purchase #4	$172.40	5.147%	$181.2734	$181.27	$181.25	$181.30
Purchase #5	$162.25	7.456%	$174.3474	$174.35	$174.35	$174.30
Purchase #6	$61.39	7.180%	$65.7978	$65.80	$65.80	$65.80
Purchase #7	$182.81	7.365%	$196.274	$196.27	$196.25	$196.30
7 purchase totals =	$882.26		$937.4960	$937.49	$937.45	$937.60