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	$247.26	5.692%	$261.334	$261.33	$261.35	$261.30
Purchase #2	$241.67	5.776%	$255.6289	$255.63	$255.65	$255.60
Purchase #3	$57.55	3.415%	$59.5153	$59.52	$59.50	$59.50
Purchase #4	$103.59	8.260%	$112.1465	$112.15	$112.15	$112.10
Purchase #5	$160.53	13.239%	$181.7826	$181.78	$181.80	$181.80
Purchase #6	$65.96	10.830%	$73.1035	$73.10	$73.10	$73.10
Purchase #7	$188.95	3.656%	$195.858	$195.86	$195.85	$195.90
7 purchase totals =	$1,065.51		$1,139.3688	$1,139.37	$1,139.40	$1,139.30