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	$105.87	7.813%	$114.1416	$114.14	$114.15	$114.10
Purchase #2	$35.31	6.301%	$37.5349	$37.53	$37.55	$37.50
Purchase #3	$55.50	4.382%	$57.932	$57.93	$57.95	$57.90
Purchase #4	$153.43	8.168%	$165.9622	$165.96	$165.95	$166.00
Purchase #5	$197.33	9.721%	$216.5124	$216.51	$216.50	$216.50
Purchase #6	$169.74	5.418%	$178.9365	$178.94	$178.95	$178.90
Purchase #7	$130.45	11.754%	$145.7831	$145.78	$145.80	$145.80
7 purchase totals =	$847.63		$916.8027	$916.79	$916.85	$916.70