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	$185.64	5.592%	$196.021	$196.02	$196.00	$196.00
Purchase #2	$134.56	9.656%	$147.5531	$147.55	$147.55	$147.60
Purchase #3	$52.65	4.265%	$54.8955	$54.90	$54.90	$54.90
Purchase #4	$225.73	7.288%	$242.1812	$242.18	$242.20	$242.20
Purchase #5	$49.61	4.603%	$51.8935	$51.89	$51.90	$51.90
Purchase #6	$243.95	5.414%	$257.1575	$257.16	$257.15	$257.20
Purchase #7	$108.47	4.650%	$113.5139	$113.51	$113.50	$113.50
7 purchase totals =	$1,000.61		$1,063.2157	$1,063.21	$1,063.20	$1,063.30