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	$112.83	10.565%	$124.7505	$124.75	$124.75	$124.80
Purchase #2	$94.51	6.478%	$100.6324	$100.63	$100.65	$100.60
Purchase #3	$189.63	12.523%	$213.3774	$213.38	$213.40	$213.40
Purchase #4	$209.82	12.705%	$236.4776	$236.48	$236.50	$236.50
Purchase #5	$37.67	11.638%	$42.054	$42.05	$42.05	$42.10
Purchase #6	$168.76	12.157%	$189.2762	$189.28	$189.30	$189.30
Purchase #7	$160.40	11.399%	$178.684	$178.68	$178.70	$178.70
7 purchase totals =	$973.62		$1,085.2521	$1,085.25	$1,085.35	$1,085.40