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	$242.68	4.380%	$253.3094	$253.31	$253.30	$253.30
Purchase #2	$175.43	4.566%	$183.4401	$183.44	$183.45	$183.40
Purchase #3	$137.69	10.392%	$151.9987	$152.00	$152.00	$152.00
Purchase #4	$95.78	5.569%	$101.114	$101.11	$101.10	$101.10
Purchase #5	$104.98	5.794%	$111.0625	$111.06	$111.05	$111.10
Purchase #6	$135.42	12.429%	$152.2514	$152.25	$152.25	$152.30
Purchase #7	$63.78	9.572%	$69.885	$69.89	$69.90	$69.90
7 purchase totals =	$955.76		$1,023.0611	$1,023.06	$1,023.05	$1,023.10