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	$109.79	4.227%	$114.4308	$114.43	$114.45	$114.40
Purchase #2	$248.90	5.372%	$262.2709	$262.27	$262.25	$262.30
Purchase #3	$204.66	7.282%	$219.5633	$219.56	$219.55	$219.60
Purchase #4	$172.50	7.141%	$184.8182	$184.82	$184.80	$184.80
Purchase #5	$78.68	6.510%	$83.8021	$83.80	$83.80	$83.80
Purchase #6	$88.80	9.140%	$96.9163	$96.92	$96.90	$96.90
Purchase #7	$50.58	3.535%	$52.368	$52.37	$52.35	$52.40
7 purchase totals =	$953.91		$1,014.1696	$1,014.17	$1,014.10	$1,014.20