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	$117.33	7.437%	$126.0558	$126.06	$126.05	$126.10
Purchase #2	$195.58	8.676%	$212.5485	$212.55	$212.55	$212.50
Purchase #3	$87.98	9.588%	$96.4155	$96.42	$96.40	$96.40
Purchase #4	$53.33	10.715%	$59.0443	$59.04	$59.05	$59.00
Purchase #5	$241.52	4.127%	$251.4875	$251.49	$251.50	$251.50
Purchase #6	$16.84	9.220%	$18.3926	$18.39	$18.40	$18.40
Purchase #7	$55.37	7.156%	$59.3323	$59.33	$59.35	$59.30
7 purchase totals =	$767.95		$823.2765	$823.28	$823.30	$823.20