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	$184.75	6.195%	$196.1953	$196.20	$196.20	$196.20
Purchase #2	$26.32	11.603%	$29.3739	$29.37	$29.35	$29.40
Purchase #3	$82.50	9.557%	$90.3845	$90.38	$90.40	$90.40
Purchase #4	$157.82	10.710%	$174.7225	$174.72	$174.70	$174.70
Purchase #5	$179.97	3.107%	$185.5617	$185.56	$185.55	$185.60
Purchase #6	$194.33	6.600%	$207.1558	$207.16	$207.15	$207.20
Purchase #7	$104.63	12.555%	$117.7663	$117.77	$117.75	$117.80
7 purchase totals =	$930.32		$1,001.1600	$1,001.16	$1,001.10	$1,001.30