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	$53.43	6.184%	$56.7341	$56.73	$56.75	$56.70
Purchase #2	$168.42	13.444%	$191.0624	$191.06	$191.05	$191.10
Purchase #3	$147.88	11.804%	$165.3358	$165.34	$165.35	$165.30
Purchase #4	$241.80	13.117%	$273.5169	$273.52	$273.50	$273.50
Purchase #5	$108.27	3.423%	$111.9761	$111.98	$112.00	$112.00
Purchase #6	$151.93	12.822%	$171.4105	$171.41	$171.40	$171.40
Purchase #7	$201.75	4.717%	$211.2665	$211.27	$211.25	$211.30
7 purchase totals =	$1,073.48		$1,181.3023	$1,181.31	$1,181.30	$1,181.30