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	$116.51	9.803%	$127.9315	$127.93	$127.95	$127.90
Purchase #2	$124.34	7.674%	$133.8819	$133.88	$133.90	$133.90
Purchase #3	$231.41	5.258%	$243.5775	$243.58	$243.60	$243.60
Purchase #4	$157.51	11.146%	$175.0661	$175.07	$175.05	$175.10
Purchase #5	$58.26	11.304%	$64.8457	$64.85	$64.85	$64.80
Purchase #6	$50.87	6.163%	$54.0051	$54.01	$54.00	$54.00
Purchase #7	$213.96	4.258%	$223.0704	$223.07	$223.05	$223.10
7 purchase totals =	$952.86		$1,022.3782	$1,022.39	$1,022.40	$1,022.40