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	$196.40	9.821%	$215.6884	$215.69	$215.70	$215.70
Purchase #2	$73.56	5.631%	$77.7022	$77.70	$77.70	$77.70
Purchase #3	$127.33	3.113%	$131.2938	$131.29	$131.30	$131.30
Purchase #4	$244.59	7.760%	$263.5702	$263.57	$263.55	$263.60
Purchase #5	$43.59	12.161%	$48.891	$48.89	$48.90	$48.90
Purchase #6	$10.76	5.346%	$11.3352	$11.34	$11.35	$11.30
Purchase #7	$157.67	9.391%	$172.4768	$172.48	$172.50	$172.50
7 purchase totals =	$853.90		$920.9576	$920.96	$921.00	$921.00