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	$198.86	13.370%	$225.4476	$225.45	$225.45	$225.40
Purchase #2	$24.38	11.708%	$27.2344	$27.23	$27.25	$27.20
Purchase #3	$107.51	3.530%	$111.3051	$111.31	$111.30	$111.30
Purchase #4	$232.75	3.173%	$240.1352	$240.14	$240.15	$240.10
Purchase #5	$188.41	11.742%	$210.5331	$210.53	$210.55	$210.50
Purchase #6	$186.97	7.172%	$200.3795	$200.38	$200.40	$200.40
Purchase #7	$17.62	13.646%	$20.0244	$20.02	$20.00	$20.00
7 purchase totals =	$956.50		$1,035.0593	$1,035.06	$1,035.10	$1,034.90