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	$201.34	12.544%	$226.5961	$226.60	$226.60	$226.60
Purchase #2	$244.56	12.708%	$275.6387	$275.64	$275.65	$275.60
Purchase #3	$44.55	3.266%	$46.005	$46.01	$46.00	$46.00
Purchase #4	$33.93	6.444%	$36.1164	$36.12	$36.10	$36.10
Purchase #5	$157.38	9.673%	$172.6034	$172.60	$172.60	$172.60
Purchase #6	$172.89	9.740%	$189.7295	$189.73	$189.75	$189.70
Purchase #7	$105.42	13.709%	$119.872	$119.87	$119.85	$119.90
7 purchase totals =	$960.07		$1,066.5611	$1,066.57	$1,066.55	$1,066.50