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	$211.74	11.116%	$235.277	$235.28	$235.30	$235.30
Purchase #2	$54.72	13.119%	$61.8987	$61.90	$61.90	$61.90
Purchase #3	$127.94	8.113%	$138.3198	$138.32	$138.30	$138.30
Purchase #4	$135.43	5.214%	$142.4913	$142.49	$142.50	$142.50
Purchase #5	$216.60	3.623%	$224.4474	$224.45	$224.45	$224.40
Purchase #6	$162.89	3.391%	$168.4136	$168.41	$168.40	$168.40
Purchase #7	$135.61	8.799%	$147.5423	$147.54	$147.55	$147.50
7 purchase totals =	$1,044.93		$1,118.3901	$1,118.39	$1,118.40	$1,118.30