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	$158.77	5.480%	$167.4706	$167.47	$167.45	$167.50
Purchase #2	$90.94	6.778%	$97.1039	$97.10	$97.10	$97.10
Purchase #3	$160.59	8.437%	$174.139	$174.14	$174.15	$174.10
Purchase #4	$241.56	7.387%	$259.404	$259.40	$259.40	$259.40
Purchase #5	$233.29	4.608%	$244.04	$244.04	$244.05	$244.00
Purchase #6	$245.68	7.410%	$263.8849	$263.88	$263.90	$263.90
Purchase #7	$17.31	6.675%	$18.4654	$18.47	$18.45	$18.50
7 purchase totals =	$1,148.14		$1,224.5078	$1,224.50	$1,224.50	$1,224.50