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	$208.39	7.119%	$223.2253	$223.23	$223.25	$223.20
Purchase #2	$220.92	5.628%	$233.3534	$233.35	$233.35	$233.40
Purchase #3	$187.90	3.206%	$193.9241	$193.92	$193.90	$193.90
Purchase #4	$131.57	11.418%	$146.5927	$146.59	$146.60	$146.60
Purchase #5	$226.54	7.336%	$243.159	$243.16	$243.15	$243.20
Purchase #6	$59.45	3.644%	$61.6164	$61.62	$61.60	$61.60
Purchase #7	$77.67	6.438%	$82.6704	$82.67	$82.65	$82.70
7 purchase totals =	$1,112.44		$1,184.5413	$1,184.54	$1,184.50	$1,184.60