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	$86.38	9.350%	$94.4565	$94.46	$94.45	$94.50
Purchase #2	$69.82	3.429%	$72.2141	$72.21	$72.20	$72.20
Purchase #3	$235.49	4.279%	$245.5666	$245.57	$245.55	$245.60
Purchase #4	$76.76	13.292%	$86.9629	$86.96	$86.95	$87.00
Purchase #5	$95.41	4.400%	$99.608	$99.61	$99.60	$99.60
Purchase #6	$236.88	3.304%	$244.7065	$244.71	$244.70	$244.70
Purchase #7	$240.42	4.292%	$250.7388	$250.74	$250.75	$250.70
7 purchase totals =	$1,041.16		$1,094.2534	$1,094.26	$1,094.20	$1,094.30