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	$203.96	3.584%	$211.2699	$211.27	$211.25	$211.30
Purchase #2	$179.87	4.874%	$188.6369	$188.64	$188.65	$188.60
Purchase #3	$41.86	3.572%	$43.3552	$43.36	$43.35	$43.40
Purchase #4	$73.56	6.149%	$78.0832	$78.08	$78.10	$78.10
Purchase #5	$44.57	13.558%	$50.6128	$50.61	$50.60	$50.60
Purchase #6	$157.75	4.117%	$164.2446	$164.24	$164.25	$164.20
Purchase #7	$163.81	13.642%	$186.157	$186.16	$186.15	$186.20
7 purchase totals =	$865.38		$922.3596	$922.36	$922.35	$922.40