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	$174.75	12.498%	$196.5903	$196.59	$196.60	$196.60
Purchase #2	$48.29	11.711%	$53.9452	$53.95	$53.95	$53.90
Purchase #3	$193.32	13.756%	$219.9131	$219.91	$219.90	$219.90
Purchase #4	$9.96	5.512%	$10.509	$10.51	$10.50	$10.50
Purchase #5	$5.68	3.732%	$5.892	$5.89	$5.90	$5.90
Purchase #6	$42.62	11.733%	$47.6206	$47.62	$47.60	$47.60
Purchase #7	$246.38	5.802%	$260.675	$260.68	$260.70	$260.70
7 purchase totals =	$721.00		$795.1452	$795.15	$795.15	$795.10