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	$90.92	5.475%	$95.8979	$95.90	$95.90	$95.90
Purchase #2	$152.58	9.530%	$167.1209	$167.12	$167.10	$167.10
Purchase #3	$212.38	7.863%	$229.0794	$229.08	$229.10	$229.10
Purchase #4	$60.25	4.400%	$62.901	$62.90	$62.90	$62.90
Purchase #5	$183.28	9.656%	$200.9775	$200.98	$201.00	$201.00
Purchase #6	$34.82	6.247%	$36.9952	$37.00	$37.00	$37.00
Purchase #7	$181.50	4.633%	$189.9089	$189.91	$189.90	$189.90
7 purchase totals =	$915.73		$982.8808	$982.89	$982.90	$982.90