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	$223.70	9.298%	$244.4996	$244.50	$244.50	$244.50
Purchase #2	$96.81	7.504%	$104.0746	$104.07	$104.05	$104.10
Purchase #3	$188.44	12.123%	$211.2846	$211.28	$211.30	$211.30
Purchase #4	$37.48	4.781%	$39.2719	$39.27	$39.25	$39.30
Purchase #5	$153.32	4.667%	$160.4754	$160.48	$160.50	$160.50
Purchase #6	$108.36	4.529%	$113.2676	$113.27	$113.25	$113.30
Purchase #7	$144.36	4.253%	$150.4996	$150.50	$150.50	$150.50
7 purchase totals =	$952.47		$1,023.3733	$1,023.37	$1,023.35	$1,023.50