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	$37.31	11.464%	$41.5872	$41.59	$41.60	$41.60
Purchase #2	$209.70	6.789%	$223.9365	$223.94	$223.95	$223.90
Purchase #3	$56.83	7.255%	$60.953	$60.95	$60.95	$61.00
Purchase #4	$171.31	9.346%	$187.3206	$187.32	$187.30	$187.30
Purchase #5	$151.91	11.426%	$169.2672	$169.27	$169.25	$169.30
Purchase #6	$145.74	4.481%	$152.2706	$152.27	$152.25	$152.30
Purchase #7	$190.63	11.584%	$212.7126	$212.71	$212.70	$212.70
7 purchase totals =	$963.43		$1,048.0477	$1,048.05	$1,048.00	$1,048.10