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	$43.98	3.759%	$45.6332	$45.63	$45.65	$45.60
Purchase #2	$40.77	11.292%	$45.3737	$45.37	$45.35	$45.40
Purchase #3	$66.63	6.114%	$70.7038	$70.70	$70.70	$70.70
Purchase #4	$26.69	8.407%	$28.9338	$28.93	$28.95	$28.90
Purchase #5	$108.64	13.362%	$123.1565	$123.16	$123.15	$123.20
Purchase #6	$205.51	11.336%	$228.8066	$228.81	$228.80	$228.80
Purchase #7	$156.44	5.126%	$164.4591	$164.46	$164.45	$164.50
7 purchase totals =	$648.66		$707.0667	$707.06	$707.05	$707.10