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	$197.92	9.609%	$216.9381	$216.94	$216.95	$216.90
Purchase #2	$141.94	3.217%	$146.5062	$146.51	$146.50	$146.50
Purchase #3	$63.31	3.684%	$65.6423	$65.64	$65.65	$65.60
Purchase #4	$58.53	5.250%	$61.6028	$61.60	$61.60	$61.60
Purchase #5	$145.73	4.618%	$152.4598	$152.46	$152.45	$152.50
Purchase #6	$136.33	4.685%	$142.7171	$142.72	$142.70	$142.70
Purchase #7	$202.56	11.344%	$225.5384	$225.54	$225.55	$225.50
7 purchase totals =	$946.32		$1,011.4047	$1,011.41	$1,011.40	$1,011.30