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	$228.27	6.445%	$242.982	$242.98	$243.00	$243.00
Purchase #2	$233.29	3.459%	$241.3595	$241.36	$241.35	$241.40
Purchase #3	$238.33	7.151%	$255.373	$255.37	$255.35	$255.40
Purchase #4	$52.79	3.242%	$54.5015	$54.50	$54.50	$54.50
Purchase #5	$174.68	3.601%	$180.9702	$180.97	$180.95	$181.00
Purchase #6	$79.37	5.789%	$83.9647	$83.96	$83.95	$84.00
Purchase #7	$157.27	10.548%	$173.8588	$173.86	$173.85	$173.90
7 purchase totals =	$1,164.00		$1,233.0097	$1,233.00	$1,232.95	$1,233.20