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	$61.63	3.743%	$63.9368	$63.94	$63.95	$63.90
Purchase #2	$146.37	7.432%	$157.2482	$157.25	$157.25	$157.20
Purchase #3	$104.33	4.457%	$108.98	$108.98	$109.00	$109.00
Purchase #4	$231.32	4.427%	$241.5605	$241.56	$241.55	$241.60
Purchase #5	$137.97	13.274%	$156.2841	$156.28	$156.30	$156.30
Purchase #6	$49.61	7.524%	$53.3427	$53.34	$53.35	$53.30
Purchase #7	$237.79	11.236%	$264.5081	$264.51	$264.50	$264.50
7 purchase totals =	$969.02		$1,045.8604	$1,045.86	$1,045.90	$1,045.80