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	$94.39	3.753%	$97.9325	$97.93	$97.95	$97.90
Purchase #2	$86.30	7.514%	$92.7846	$92.78	$92.80	$92.80
Purchase #3	$191.88	4.458%	$200.434	$200.43	$200.45	$200.40
Purchase #4	$179.88	4.572%	$188.1041	$188.10	$188.10	$188.10
Purchase #5	$154.42	3.652%	$160.0594	$160.06	$160.05	$160.10
Purchase #6	$149.96	10.197%	$165.2514	$165.25	$165.25	$165.30
Purchase #7	$139.93	7.541%	$150.4821	$150.48	$150.50	$150.50
7 purchase totals =	$996.76		$1,055.0481	$1,055.03	$1,055.10	$1,055.10