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	$213.39	9.631%	$233.9416	$233.94	$233.95	$233.90
Purchase #2	$221.37	5.592%	$233.749	$233.75	$233.75	$233.70
Purchase #3	$178.55	3.738%	$185.2242	$185.22	$185.20	$185.20
Purchase #4	$35.60	8.272%	$38.5448	$38.54	$38.55	$38.50
Purchase #5	$234.65	3.619%	$243.142	$243.14	$243.15	$243.10
Purchase #6	$26.54	5.124%	$27.8999	$27.90	$27.90	$27.90
Purchase #7	$137.29	7.505%	$147.5936	$147.59	$147.60	$147.60
7 purchase totals =	$1,047.39		$1,110.0951	$1,110.08	$1,110.10	$1,109.90