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	$149.35	12.440%	$167.9291	$167.93	$167.95	$167.90
Purchase #2	$166.82	11.196%	$185.4972	$185.50	$185.50	$185.50
Purchase #3	$205.58	3.504%	$212.7835	$212.78	$212.80	$212.80
Purchase #4	$98.91	3.454%	$102.3264	$102.33	$102.35	$102.30
Purchase #5	$67.41	5.118%	$70.86	$70.86	$70.85	$70.90
Purchase #6	$80.40	6.768%	$85.8415	$85.84	$85.85	$85.80
Purchase #7	$229.56	6.216%	$243.8294	$243.83	$243.85	$243.80
7 purchase totals =	$998.03		$1,069.0671	$1,069.07	$1,069.15	$1,069.00