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	$82.36	4.315%	$85.9138	$85.91	$85.90	$85.90
Purchase #2	$59.53	5.163%	$62.6035	$62.60	$62.60	$62.60
Purchase #3	$59.78	7.362%	$64.181	$64.18	$64.20	$64.20
Purchase #4	$118.29	4.769%	$123.9313	$123.93	$123.95	$123.90
Purchase #5	$44.38	8.656%	$48.2215	$48.22	$48.20	$48.20
Purchase #6	$222.27	4.716%	$232.7523	$232.75	$232.75	$232.80
Purchase #7	$97.33	4.261%	$101.4772	$101.48	$101.50	$101.50
7 purchase totals =	$683.94		$719.0806	$719.07	$719.10	$719.10