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	$140.85	4.555%	$147.2657	$147.27	$147.25	$147.30
Purchase #2	$63.60	6.574%	$67.7811	$67.78	$67.80	$67.80
Purchase #3	$179.43	5.572%	$189.4278	$189.43	$189.45	$189.40
Purchase #4	$123.33	12.773%	$139.0829	$139.08	$139.10	$139.10
Purchase #5	$112.47	3.250%	$116.1253	$116.13	$116.15	$116.10
Purchase #6	$142.73	11.500%	$159.144	$159.14	$159.15	$159.10
Purchase #7	$211.45	7.453%	$227.2094	$227.21	$227.20	$227.20
7 purchase totals =	$973.86		$1,046.0362	$1,046.04	$1,046.10	$1,046.00