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	$198.39	3.698%	$205.7265	$205.73	$205.75	$205.70
Purchase #2	$141.50	8.365%	$153.3365	$153.34	$153.35	$153.30
Purchase #3	$31.64	7.256%	$33.9358	$33.94	$33.95	$33.90
Purchase #4	$57.63	3.759%	$59.7963	$59.80	$59.80	$59.80
Purchase #5	$227.93	5.741%	$241.0155	$241.02	$241.00	$241.00
Purchase #6	$196.90	13.271%	$223.0306	$223.03	$223.05	$223.00
Purchase #7	$127.73	6.868%	$136.5025	$136.50	$136.50	$136.50
7 purchase totals =	$981.72		$1,053.3437	$1,053.36	$1,053.40	$1,053.20