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	$216.90	3.851%	$225.2528	$225.25	$225.25	$225.30
Purchase #2	$92.39	3.810%	$95.9101	$95.91	$95.90	$95.90
Purchase #3	$100.34	8.811%	$109.181	$109.18	$109.20	$109.20
Purchase #4	$202.28	12.227%	$227.0128	$227.01	$227.00	$227.00
Purchase #5	$159.52	12.250%	$179.0612	$179.06	$179.05	$179.10
Purchase #6	$216.80	9.113%	$236.557	$236.56	$236.55	$236.60
Purchase #7	$100.53	12.188%	$112.7826	$112.78	$112.80	$112.80
7 purchase totals =	$1,088.76		$1,185.7575	$1,185.75	$1,185.75	$1,185.90