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	$83.86	10.793%	$92.911	$92.91	$92.90	$92.90
Purchase #2	$141.46	12.298%	$158.8568	$158.86	$158.85	$158.90
Purchase #3	$164.42	13.466%	$186.5608	$186.56	$186.55	$186.60
Purchase #4	$168.61	12.606%	$189.865	$189.87	$189.85	$189.90
Purchase #5	$180.26	11.373%	$200.761	$200.76	$200.75	$200.80
Purchase #6	$155.37	12.647%	$175.0196	$175.02	$175.00	$175.00
Purchase #7	$177.94	7.691%	$191.6254	$191.63	$191.65	$191.60
7 purchase totals =	$1,071.92		$1,195.5996	$1,195.61	$1,195.55	$1,195.70