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	$191.38	8.837%	$208.2923	$208.29	$208.30	$208.30
Purchase #2	$51.37	5.408%	$54.1481	$54.15	$54.15	$54.10
Purchase #3	$182.80	6.245%	$194.2159	$194.22	$194.20	$194.20
Purchase #4	$138.32	11.819%	$154.668	$154.67	$154.65	$154.70
Purchase #5	$156.64	6.217%	$166.3783	$166.38	$166.40	$166.40
Purchase #6	$65.51	9.333%	$71.624	$71.62	$71.60	$71.60
Purchase #7	$185.35	10.650%	$205.0898	$205.09	$205.10	$205.10
7 purchase totals =	$971.37		$1,054.4164	$1,054.42	$1,054.40	$1,054.40