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	$40.95	12.626%	$46.1203	$46.12	$46.10	$46.10
Purchase #2	$215.64	3.309%	$222.7755	$222.78	$222.80	$222.80
Purchase #3	$81.29	5.728%	$85.9463	$85.95	$85.95	$85.90
Purchase #4	$92.64	6.357%	$98.5291	$98.53	$98.55	$98.50
Purchase #5	$13.35	13.257%	$15.1198	$15.12	$15.10	$15.10
Purchase #6	$66.81	6.727%	$71.3043	$71.30	$71.30	$71.30
Purchase #7	$196.44	11.644%	$219.3135	$219.31	$219.30	$219.30
7 purchase totals =	$707.12		$759.1088	$759.11	$759.10	$759.00