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	$77.69	10.611%	$85.9337	$85.93	$85.95	$85.90
Purchase #2	$93.62	7.280%	$100.4355	$100.44	$100.45	$100.40
Purchase #3	$152.38	10.797%	$168.8325	$168.83	$168.85	$168.80
Purchase #4	$36.55	3.743%	$37.9181	$37.92	$37.90	$37.90
Purchase #5	$159.62	8.396%	$173.0217	$173.02	$173.00	$173.00
Purchase #6	$103.32	3.667%	$107.1087	$107.11	$107.10	$107.10
Purchase #7	$249.71	7.345%	$268.0512	$268.05	$268.05	$268.10
7 purchase totals =	$872.89		$941.3014	$941.30	$941.30	$941.20