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	$144.99	5.264%	$152.6223	$152.62	$152.60	$152.60
Purchase #2	$107.88	5.532%	$113.8479	$113.85	$113.85	$113.80
Purchase #3	$96.59	5.533%	$101.9343	$101.93	$101.95	$101.90
Purchase #4	$54.35	9.175%	$59.3366	$59.34	$59.35	$59.30
Purchase #5	$158.67	10.857%	$175.8968	$175.90	$175.90	$175.90
Purchase #6	$162.69	6.254%	$172.8646	$172.86	$172.85	$172.90
Purchase #7	$7.86	13.740%	$8.94	$8.94	$8.95	$8.90
7 purchase totals =	$733.03		$785.4425	$785.44	$785.45	$785.30