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	$105.71	3.501%	$109.4109	$109.41	$109.40	$109.40
Purchase #2	$186.31	3.429%	$192.6986	$192.70	$192.70	$192.70
Purchase #3	$12.61	4.244%	$13.1452	$13.15	$13.15	$13.10
Purchase #4	$123.88	10.558%	$136.9593	$136.96	$136.95	$137.00
Purchase #5	$46.26	11.107%	$51.3981	$51.40	$51.40	$51.40
Purchase #6	$83.88	3.450%	$86.7739	$86.77	$86.75	$86.80
Purchase #7	$98.52	11.209%	$109.5631	$109.56	$109.55	$109.60
7 purchase totals =	$657.17		$699.9491	$699.95	$699.90	$700.00