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	$177.80	10.128%	$195.8076	$195.81	$195.80	$195.80
Purchase #2	$216.32	13.507%	$245.5383	$245.54	$245.55	$245.50
Purchase #3	$141.63	12.597%	$159.4711	$159.47	$159.45	$159.50
Purchase #4	$204.64	6.582%	$218.1094	$218.11	$218.10	$218.10
Purchase #5	$179.89	9.350%	$196.7097	$196.71	$196.70	$196.70
Purchase #6	$33.98	11.192%	$37.783	$37.78	$37.80	$37.80
Purchase #7	$144.97	11.757%	$162.0141	$162.01	$162.00	$162.00
7 purchase totals =	$1,099.23		$1,215.4332	$1,215.43	$1,215.40	$1,215.40