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	$186.54	5.344%	$196.5087	$196.51	$196.50	$196.50
Purchase #2	$222.96	5.190%	$234.5316	$234.53	$234.55	$234.50
Purchase #3	$13.74	4.206%	$14.3179	$14.32	$14.30	$14.30
Purchase #4	$194.35	13.653%	$220.8846	$220.88	$220.90	$220.90
Purchase #5	$100.30	11.556%	$111.8907	$111.89	$111.90	$111.90
Purchase #6	$235.87	12.228%	$264.7122	$264.71	$264.70	$264.70
Purchase #7	$18.93	11.338%	$21.0763	$21.08	$21.10	$21.10
7 purchase totals =	$972.69		$1,063.9220	$1,063.92	$1,063.95	$1,063.90