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	$57.32	6.340%	$60.9541	$60.95	$60.95	$61.00
Purchase #2	$32.47	11.800%	$36.3015	$36.30	$36.30	$36.30
Purchase #3	$150.69	6.507%	$160.4954	$160.50	$160.50	$160.50
Purchase #4	$83.32	8.618%	$90.5005	$90.50	$90.50	$90.50
Purchase #5	$235.42	11.279%	$261.973	$261.97	$261.95	$262.00
Purchase #6	$161.61	11.811%	$180.6978	$180.70	$180.70	$180.70
Purchase #7	$97.27	6.326%	$103.4233	$103.42	$103.40	$103.40
7 purchase totals =	$818.10		$894.3456	$894.34	$894.30	$894.40