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	$88.87	7.844%	$95.841	$95.84	$95.85	$95.80
Purchase #2	$182.46	5.507%	$192.5081	$192.51	$192.50	$192.50
Purchase #3	$129.73	3.684%	$134.5093	$134.51	$134.50	$134.50
Purchase #4	$149.37	3.460%	$154.5382	$154.54	$154.55	$154.50
Purchase #5	$62.35	3.296%	$64.4051	$64.41	$64.40	$64.40
Purchase #6	$154.38	6.245%	$164.021	$164.02	$164.00	$164.00
Purchase #7	$188.68	4.360%	$196.9064	$196.91	$196.90	$196.90
7 purchase totals =	$955.84		$1,002.7291	$1,002.74	$1,002.70	$1,002.60