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	$147.30	4.287%	$153.6148	$153.61	$153.60	$153.60
Purchase #2	$112.63	4.454%	$117.6465	$117.65	$117.65	$117.60
Purchase #3	$173.90	3.214%	$179.4891	$179.49	$179.50	$179.50
Purchase #4	$79.28	7.346%	$85.1039	$85.10	$85.10	$85.10
Purchase #5	$80.78	10.493%	$89.2562	$89.26	$89.25	$89.30
Purchase #6	$236.49	10.548%	$261.435	$261.44	$261.45	$261.40
Purchase #7	$92.81	4.436%	$96.9271	$96.93	$96.95	$96.90
7 purchase totals =	$923.19		$983.4726	$983.48	$983.50	$983.40