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	$109.32	4.839%	$114.61	$114.61	$114.60	$114.60
Purchase #2	$127.98	11.403%	$142.5736	$142.57	$142.55	$142.60
Purchase #3	$61.91	5.406%	$65.2569	$65.26	$65.25	$65.30
Purchase #4	$22.55	4.713%	$23.6128	$23.61	$23.60	$23.60
Purchase #5	$243.57	7.593%	$262.0643	$262.06	$262.05	$262.10
Purchase #6	$244.57	12.851%	$275.9997	$276.00	$276.00	$276.00
Purchase #7	$131.72	6.548%	$140.345	$140.35	$140.35	$140.30
7 purchase totals =	$941.62		$1,024.4623	$1,024.46	$1,024.40	$1,024.50