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	$223.70	10.130%	$246.3608	$246.36	$246.35	$246.40
Purchase #2	$213.98	9.107%	$233.4672	$233.47	$233.45	$233.50
Purchase #3	$63.32	13.106%	$71.6187	$71.62	$71.60	$71.60
Purchase #4	$188.96	7.187%	$202.5406	$202.54	$202.55	$202.50
Purchase #5	$196.25	6.250%	$208.5156	$208.52	$208.50	$208.50
Purchase #6	$43.53	7.853%	$46.9484	$46.95	$46.95	$46.90
Purchase #7	$174.29	7.215%	$186.865	$186.87	$186.85	$186.90
7 purchase totals =	$1,104.03		$1,196.3163	$1,196.33	$1,196.25	$1,196.30