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	$181.25	6.265%	$192.6053	$192.61	$192.60	$192.60
Purchase #2	$32.30	9.105%	$35.2409	$35.24	$35.25	$35.20
Purchase #3	$142.82	5.633%	$150.8651	$150.87	$150.85	$150.90
Purchase #4	$162.39	4.490%	$169.6813	$169.68	$169.70	$169.70
Purchase #5	$153.89	11.208%	$171.138	$171.14	$171.15	$171.10
Purchase #6	$180.28	11.213%	$200.4948	$200.49	$200.50	$200.50
Purchase #7	$170.97	10.329%	$188.6295	$188.63	$188.65	$188.60
7 purchase totals =	$1,023.90		$1,108.6549	$1,108.66	$1,108.70	$1,108.60