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	$141.69	7.763%	$152.6894	$152.69	$152.70	$152.70
Purchase #2	$204.45	3.234%	$211.0619	$211.06	$211.05	$211.10
Purchase #3	$186.66	8.115%	$201.8075	$201.81	$201.80	$201.80
Purchase #4	$82.78	9.483%	$90.63	$90.63	$90.65	$90.60
Purchase #5	$95.38	6.695%	$101.7657	$101.77	$101.75	$101.80
Purchase #6	$231.43	11.384%	$257.776	$257.78	$257.80	$257.80
Purchase #7	$123.67	6.622%	$131.8594	$131.86	$131.85	$131.90
7 purchase totals =	$1,066.06		$1,147.5899	$1,147.60	$1,147.60	$1,147.70