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	$68.35	5.267%	$71.95	$71.95	$71.95	$72.00
Purchase #2	$54.97	12.386%	$61.7786	$61.78	$61.80	$61.80
Purchase #3	$38.55	4.464%	$40.2709	$40.27	$40.25	$40.30
Purchase #4	$175.57	9.816%	$192.804	$192.80	$192.80	$192.80
Purchase #5	$64.87	12.373%	$72.8964	$72.90	$72.90	$72.90
Purchase #6	$226.54	3.764%	$235.067	$235.07	$235.05	$235.10
Purchase #7	$35.58	10.399%	$39.28	$39.28	$39.30	$39.30
7 purchase totals =	$664.43		$714.0469	$714.05	$714.05	$714.20