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	$196.47	5.820%	$207.9046	$207.90	$207.90	$207.90
Purchase #2	$192.42	5.704%	$203.3956	$203.40	$203.40	$203.40
Purchase #3	$36.96	4.342%	$38.5648	$38.56	$38.55	$38.60
Purchase #4	$178.92	9.655%	$196.1947	$196.19	$196.20	$196.20
Purchase #5	$64.40	12.515%	$72.4597	$72.46	$72.45	$72.50
Purchase #6	$16.94	9.465%	$18.5434	$18.54	$18.55	$18.50
Purchase #7	$159.28	5.864%	$168.6202	$168.62	$168.60	$168.60
7 purchase totals =	$845.39		$905.6830	$905.67	$905.65	$905.70