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	$226.31	7.698%	$243.7313	$243.73	$243.75	$243.70
Purchase #2	$186.34	7.519%	$200.3509	$200.35	$200.35	$200.40
Purchase #3	$117.31	5.405%	$123.6506	$123.65	$123.65	$123.70
Purchase #4	$155.45	5.704%	$164.3169	$164.32	$164.30	$164.30
Purchase #5	$64.62	10.548%	$71.4361	$71.44	$71.45	$71.40
Purchase #6	$89.48	10.673%	$99.0302	$99.03	$99.05	$99.00
Purchase #7	$146.40	13.750%	$166.53	$166.53	$166.55	$166.50
7 purchase totals =	$985.91		$1,069.0460	$1,069.05	$1,069.10	$1,069.00