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	$96.42	5.625%	$101.8436	$101.84	$101.85	$101.80
Purchase #2	$216.56	5.774%	$229.0642	$229.06	$229.05	$229.10
Purchase #3	$12.33	12.704%	$13.8964	$13.90	$13.90	$13.90
Purchase #4	$136.35	6.179%	$144.7751	$144.78	$144.80	$144.80
Purchase #5	$226.73	12.626%	$255.3569	$255.36	$255.35	$255.40
Purchase #6	$162.82	6.103%	$172.7569	$172.76	$172.75	$172.80
Purchase #7	$249.61	4.628%	$261.162	$261.16	$261.15	$261.20
7 purchase totals =	$1,100.82		$1,178.8551	$1,178.86	$1,178.85	$1,179.00