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	$213.84	11.702%	$238.8636	$238.86	$238.85	$238.90
Purchase #2	$237.76	5.344%	$250.4659	$250.47	$250.45	$250.50
Purchase #3	$185.57	9.435%	$203.0785	$203.08	$203.10	$203.10
Purchase #4	$174.78	11.496%	$194.8727	$194.87	$194.85	$194.90
Purchase #5	$205.88	3.411%	$212.9026	$212.90	$212.90	$212.90
Purchase #6	$168.36	6.785%	$179.7832	$179.78	$179.80	$179.80
Purchase #7	$95.35	10.443%	$105.3074	$105.31	$105.30	$105.30
7 purchase totals =	$1,281.54		$1,385.2739	$1,385.27	$1,385.25	$1,385.40