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	$86.42	12.288%	$97.0393	$97.04	$97.05	$97.00
Purchase #2	$182.25	6.517%	$194.1272	$194.13	$194.15	$194.10
Purchase #3	$154.62	8.312%	$167.472	$167.47	$167.45	$167.50
Purchase #4	$137.43	6.502%	$146.3657	$146.37	$146.35	$146.40
Purchase #5	$164.76	8.805%	$179.2671	$179.27	$179.25	$179.30
Purchase #6	$72.91	12.490%	$82.0165	$82.02	$82.00	$82.00
Purchase #7	$176.30	12.662%	$198.6231	$198.62	$198.60	$198.60
7 purchase totals =	$974.69		$1,064.9109	$1,064.92	$1,064.85	$1,064.90