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	$185.94	7.716%	$200.2871	$200.29	$200.30	$200.30
Purchase #2	$231.35	7.109%	$247.7967	$247.80	$247.80	$247.80
Purchase #3	$163.64	5.148%	$172.0642	$172.06	$172.05	$172.10
Purchase #4	$40.55	12.408%	$45.5814	$45.58	$45.60	$45.60
Purchase #5	$202.52	5.624%	$213.9097	$213.91	$213.90	$213.90
Purchase #6	$209.34	7.553%	$225.1515	$225.15	$225.15	$225.20
Purchase #7	$84.38	5.620%	$89.1222	$89.12	$89.10	$89.10
7 purchase totals =	$1,117.72		$1,193.9128	$1,193.91	$1,193.90	$1,194.00