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	$154.49	5.404%	$162.8386	$162.84	$162.85	$162.80
Purchase #2	$40.83	7.314%	$43.8163	$43.82	$43.80	$43.80
Purchase #3	$155.27	7.764%	$167.3252	$167.33	$167.35	$167.30
Purchase #4	$159.33	7.785%	$171.7338	$171.73	$171.75	$171.70
Purchase #5	$103.28	6.202%	$109.6854	$109.69	$109.70	$109.70
Purchase #6	$229.70	5.630%	$242.6321	$242.63	$242.65	$242.60
Purchase #7	$192.42	4.267%	$200.6306	$200.63	$200.65	$200.60
7 purchase totals =	$1,035.32		$1,098.6620	$1,098.67	$1,098.75	$1,098.50