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	$228.93	4.369%	$238.932	$238.93	$238.95	$238.90
Purchase #2	$82.38	4.684%	$86.2387	$86.24	$86.25	$86.20
Purchase #3	$209.91	4.488%	$219.3308	$219.33	$219.35	$219.30
Purchase #4	$121.65	13.360%	$137.9024	$137.90	$137.90	$137.90
Purchase #5	$114.73	10.856%	$127.1851	$127.19	$127.20	$127.20
Purchase #6	$221.98	7.438%	$238.4909	$238.49	$238.50	$238.50
Purchase #7	$228.57	4.780%	$239.4956	$239.50	$239.50	$239.50
7 purchase totals =	$1,208.15		$1,287.5755	$1,287.58	$1,287.65	$1,287.50