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	$98.55	11.561%	$109.9434	$109.94	$109.95	$109.90
Purchase #2	$43.32	12.334%	$48.6631	$48.66	$48.65	$48.70
Purchase #3	$152.55	12.150%	$171.0848	$171.08	$171.10	$171.10
Purchase #4	$114.52	11.416%	$127.5936	$127.59	$127.60	$127.60
Purchase #5	$213.75	4.796%	$224.0015	$224.00	$224.00	$224.00
Purchase #6	$126.29	12.408%	$141.9601	$141.96	$141.95	$142.00
Purchase #7	$202.49	13.670%	$230.1704	$230.17	$230.15	$230.20
7 purchase totals =	$951.47		$1,053.4169	$1,053.40	$1,053.40	$1,053.50