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	$148.30	11.616%	$165.5265	$165.53	$165.55	$165.50
Purchase #2	$26.89	12.520%	$30.2566	$30.26	$30.25	$30.30
Purchase #3	$32.90	12.527%	$37.0214	$37.02	$37.00	$37.00
Purchase #4	$223.64	9.683%	$245.2951	$245.30	$245.30	$245.30
Purchase #5	$139.64	9.210%	$152.5008	$152.50	$152.50	$152.50
Purchase #6	$180.76	5.253%	$190.2553	$190.26	$190.25	$190.30
Purchase #7	$200.92	7.157%	$215.2998	$215.30	$215.30	$215.30
7 purchase totals =	$953.05		$1,036.1555	$1,036.17	$1,036.15	$1,036.20