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	$125.92	4.323%	$131.3635	$131.36	$131.35	$131.40
Purchase #2	$216.46	4.337%	$225.8479	$225.85	$225.85	$225.80
Purchase #3	$136.55	10.859%	$151.378	$151.38	$151.40	$151.40
Purchase #4	$62.55	11.240%	$69.5806	$69.58	$69.60	$69.60
Purchase #5	$157.39	6.304%	$167.3119	$167.31	$167.30	$167.30
Purchase #6	$224.27	11.508%	$250.079	$250.08	$250.10	$250.10
Purchase #7	$35.32	9.332%	$38.6161	$38.62	$38.60	$38.60
7 purchase totals =	$958.46		$1,034.1770	$1,034.18	$1,034.20	$1,034.20