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	$119.58	6.247%	$127.0502	$127.05	$127.05	$127.10
Purchase #2	$104.74	10.242%	$115.4675	$115.47	$115.45	$115.50
Purchase #3	$87.89	3.419%	$90.895	$90.90	$90.90	$90.90
Purchase #4	$191.57	11.483%	$213.568	$213.57	$213.55	$213.60
Purchase #5	$136.45	13.625%	$155.0413	$155.04	$155.05	$155.00
Purchase #6	$104.65	8.302%	$113.338	$113.34	$113.35	$113.30
Purchase #7	$242.59	5.676%	$256.3594	$256.36	$256.35	$256.40
7 purchase totals =	$987.47		$1,071.7194	$1,071.73	$1,071.70	$1,071.80