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	$236.78	7.646%	$254.8842	$254.88	$254.90	$254.90
Purchase #2	$182.32	3.293%	$188.3238	$188.32	$188.30	$188.30
Purchase #3	$60.89	7.265%	$65.3137	$65.31	$65.30	$65.30
Purchase #4	$210.94	11.443%	$235.0779	$235.08	$235.10	$235.10
Purchase #5	$155.41	3.156%	$160.3147	$160.31	$160.30	$160.30
Purchase #6	$82.99	4.568%	$86.781	$86.78	$86.80	$86.80
Purchase #7	$30.88	9.681%	$33.8695	$33.87	$33.85	$33.90
7 purchase totals =	$960.21		$1,024.5648	$1,024.55	$1,024.55	$1,024.60