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	$177.86	9.650%	$195.0235	$195.02	$195.00	$195.00
Purchase #2	$225.90	11.382%	$251.6119	$251.61	$251.60	$251.60
Purchase #3	$164.50	11.386%	$183.23	$183.23	$183.25	$183.20
Purchase #4	$92.46	7.421%	$99.3215	$99.32	$99.30	$99.30
Purchase #5	$91.57	12.544%	$103.0565	$103.06	$103.05	$103.10
Purchase #6	$78.52	5.359%	$82.7279	$82.73	$82.75	$82.70
Purchase #7	$164.86	8.330%	$178.5928	$178.59	$178.60	$178.60
7 purchase totals =	$995.67		$1,093.5641	$1,093.56	$1,093.55	$1,093.50