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	$113.39	12.834%	$127.9425	$127.94	$127.95	$127.90
Purchase #2	$245.53	6.608%	$261.7546	$261.75	$261.75	$261.80
Purchase #3	$33.53	6.384%	$35.6706	$35.67	$35.65	$35.70
Purchase #4	$211.68	10.225%	$233.3243	$233.32	$233.30	$233.30
Purchase #5	$216.96	6.271%	$230.5656	$230.57	$230.55	$230.60
Purchase #6	$136.40	7.371%	$146.454	$146.45	$146.45	$146.50
Purchase #7	$36.38	6.794%	$38.8517	$38.85	$38.85	$38.90
7 purchase totals =	$993.87		$1,074.5633	$1,074.55	$1,074.50	$1,074.70