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	$102.41	9.343%	$111.9782	$111.98	$112.00	$112.00
Purchase #2	$134.33	6.379%	$142.8989	$142.90	$142.90	$142.90
Purchase #3	$189.50	11.472%	$211.2394	$211.24	$211.25	$211.20
Purchase #4	$237.34	5.564%	$250.5456	$250.55	$250.55	$250.50
Purchase #5	$26.94	6.783%	$28.7673	$28.77	$28.75	$28.80
Purchase #6	$217.76	13.705%	$247.604	$247.60	$247.60	$247.60
Purchase #7	$96.62	5.581%	$102.0124	$102.01	$102.00	$102.00
7 purchase totals =	$1,004.90		$1,095.0458	$1,095.05	$1,095.05	$1,095.00