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	$85.72	7.712%	$92.3307	$92.33	$92.35	$92.30
Purchase #2	$186.86	13.626%	$212.3215	$212.32	$212.30	$212.30
Purchase #3	$171.45	13.599%	$194.7655	$194.77	$194.75	$194.80
Purchase #4	$152.49	10.674%	$168.7668	$168.77	$168.75	$168.80
Purchase #5	$119.83	6.640%	$127.7867	$127.79	$127.80	$127.80
Purchase #6	$10.75	5.282%	$11.3178	$11.32	$11.30	$11.30
Purchase #7	$168.32	12.671%	$189.6478	$189.65	$189.65	$189.60
7 purchase totals =	$895.42		$996.9368	$996.95	$996.90	$996.90