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	$196.56	8.120%	$212.5207	$212.52	$212.50	$212.50
Purchase #2	$36.32	10.463%	$40.1202	$40.12	$40.10	$40.10
Purchase #3	$229.43	5.112%	$241.1585	$241.16	$241.15	$241.20
Purchase #4	$84.70	5.793%	$89.6067	$89.61	$89.60	$89.60
Purchase #5	$222.86	5.443%	$234.9903	$234.99	$235.00	$235.00
Purchase #6	$13.63	8.296%	$14.7607	$14.76	$14.75	$14.80
Purchase #7	$55.47	6.766%	$59.2231	$59.22	$59.20	$59.20
7 purchase totals =	$838.97		$892.3802	$892.38	$892.30	$892.40