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	$58.75	4.441%	$61.3591	$61.36	$61.35	$61.40
Purchase #2	$60.92	7.602%	$65.5511	$65.55	$65.55	$65.60
Purchase #3	$144.43	5.669%	$152.6177	$152.62	$152.60	$152.60
Purchase #4	$159.38	9.373%	$174.3187	$174.32	$174.30	$174.30
Purchase #5	$241.33	10.733%	$267.2319	$267.23	$267.25	$267.20
Purchase #6	$180.76	8.861%	$196.7771	$196.78	$196.80	$196.80
Purchase #7	$101.88	6.695%	$108.7009	$108.70	$108.70	$108.70
7 purchase totals =	$947.45		$1,026.5565	$1,026.56	$1,026.55	$1,026.60