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	$166.67	11.425%	$185.712	$185.71	$185.70	$185.70
Purchase #2	$186.83	12.565%	$210.3052	$210.31	$210.30	$210.30
Purchase #3	$142.26	9.160%	$155.291	$155.29	$155.30	$155.30
Purchase #4	$222.98	9.413%	$243.9691	$243.97	$243.95	$244.00
Purchase #5	$59.25	13.521%	$67.2612	$67.26	$67.25	$67.30
Purchase #6	$247.66	9.656%	$271.574	$271.57	$271.55	$271.60
Purchase #7	$59.46	13.211%	$67.3153	$67.32	$67.30	$67.30
7 purchase totals =	$1,085.11		$1,201.4278	$1,201.43	$1,201.35	$1,201.50