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	$205.52	5.138%	$216.0796	$216.08	$216.10	$216.10
Purchase #2	$11.27	5.351%	$11.8731	$11.87	$11.85	$11.90
Purchase #3	$186.48	5.497%	$196.7308	$196.73	$196.75	$196.70
Purchase #4	$186.61	6.568%	$198.8665	$198.87	$198.85	$198.90
Purchase #5	$233.54	13.846%	$265.8759	$265.88	$265.90	$265.90
Purchase #6	$56.33	9.658%	$61.7704	$61.77	$61.75	$61.80
Purchase #7	$178.70	9.801%	$196.2144	$196.21	$196.20	$196.20
7 purchase totals =	$1,058.45		$1,147.4107	$1,147.41	$1,147.40	$1,147.50