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	$87.39	4.625%	$91.4318	$91.43	$91.45	$91.40
Purchase #2	$61.60	11.365%	$68.6008	$68.60	$68.60	$68.60
Purchase #3	$157.53	9.321%	$172.2134	$172.21	$172.20	$172.20
Purchase #4	$188.64	4.188%	$196.5402	$196.54	$196.55	$196.50
Purchase #5	$157.31	6.643%	$167.7601	$167.76	$167.75	$167.80
Purchase #6	$133.28	12.817%	$150.3625	$150.36	$150.35	$150.40
Purchase #7	$186.66	13.820%	$212.4564	$212.46	$212.45	$212.50
7 purchase totals =	$972.41		$1,059.3652	$1,059.36	$1,059.35	$1,059.40