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	$191.35	8.540%	$207.6913	$207.69	$207.70	$207.70
Purchase #2	$166.28	3.545%	$172.1746	$172.17	$172.15	$172.20
Purchase #3	$50.58	7.329%	$54.287	$54.29	$54.30	$54.30
Purchase #4	$45.89	9.289%	$50.1527	$50.15	$50.15	$50.20
Purchase #5	$101.96	3.768%	$105.8019	$105.80	$105.80	$105.80
Purchase #6	$42.36	7.413%	$45.5001	$45.50	$45.50	$45.50
Purchase #7	$209.98	3.633%	$217.6086	$217.61	$217.60	$217.60
7 purchase totals =	$808.40		$853.2162	$853.21	$853.20	$853.30