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	$218.87	3.284%	$226.0577	$226.06	$226.05	$226.10
Purchase #2	$231.82	7.131%	$248.3511	$248.35	$248.35	$248.40
Purchase #3	$173.94	6.760%	$185.6983	$185.70	$185.70	$185.70
Purchase #4	$184.43	6.438%	$196.3036	$196.30	$196.30	$196.30
Purchase #5	$93.60	5.246%	$98.5103	$98.51	$98.50	$98.50
Purchase #6	$102.82	6.706%	$109.7151	$109.72	$109.70	$109.70
Purchase #7	$178.54	10.116%	$196.6011	$196.60	$196.60	$196.60
7 purchase totals =	$1,184.02		$1,261.2372	$1,261.24	$1,261.20	$1,261.30