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	$100.59	13.414%	$114.0831	$114.08	$114.10	$114.10
Purchase #2	$137.30	10.106%	$151.1755	$151.18	$151.20	$151.20
Purchase #3	$248.32	13.245%	$281.21	$281.21	$281.20	$281.20
Purchase #4	$214.86	13.363%	$243.5717	$243.57	$243.55	$243.60
Purchase #5	$190.52	10.583%	$210.6827	$210.68	$210.70	$210.70
Purchase #6	$241.56	9.510%	$264.5324	$264.53	$264.55	$264.50
Purchase #7	$176.74	13.284%	$200.2181	$200.22	$200.20	$200.20
7 purchase totals =	$1,309.89		$1,465.4735	$1,465.47	$1,465.50	$1,465.50