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	$168.57	9.349%	$184.3296	$184.33	$184.35	$184.30
Purchase #2	$72.41	13.621%	$82.273	$82.27	$82.25	$82.30
Purchase #3	$34.72	13.535%	$39.4194	$39.42	$39.40	$39.40
Purchase #4	$232.59	7.167%	$249.2597	$249.26	$249.25	$249.30
Purchase #5	$62.90	13.738%	$71.5412	$71.54	$71.55	$71.50
Purchase #6	$217.98	12.380%	$244.9659	$244.97	$244.95	$245.00
Purchase #7	$169.44	7.460%	$182.0802	$182.08	$182.10	$182.10
7 purchase totals =	$958.61		$1,053.8690	$1,053.87	$1,053.85	$1,053.90