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	$101.85	5.299%	$107.247	$107.25	$107.25	$107.20
Purchase #2	$191.53	12.857%	$216.155	$216.16	$216.15	$216.20
Purchase #3	$149.71	9.848%	$164.4534	$164.45	$164.45	$164.50
Purchase #4	$136.55	7.161%	$146.3283	$146.33	$146.35	$146.30
Purchase #5	$138.72	8.460%	$150.4557	$150.46	$150.45	$150.50
Purchase #6	$192.77	7.846%	$207.8947	$207.89	$207.90	$207.90
Purchase #7	$106.55	11.264%	$118.5518	$118.55	$118.55	$118.60
7 purchase totals =	$1,017.68		$1,111.0859	$1,111.09	$1,111.10	$1,111.20