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	$210.80	7.567%	$226.7512	$226.75	$226.75	$226.80
Purchase #2	$127.53	13.343%	$144.5463	$144.55	$144.55	$144.50
Purchase #3	$199.25	3.652%	$206.5266	$206.53	$206.55	$206.50
Purchase #4	$137.32	6.706%	$146.5287	$146.53	$146.55	$146.50
Purchase #5	$34.27	6.132%	$36.3714	$36.37	$36.35	$36.40
Purchase #6	$213.37	4.195%	$222.3209	$222.32	$222.30	$222.30
Purchase #7	$38.47	4.411%	$40.1669	$40.17	$40.15	$40.20
7 purchase totals =	$961.01		$1,023.2120	$1,023.22	$1,023.20	$1,023.20