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	$187.32	9.852%	$205.7748	$205.77	$205.75	$205.80
Purchase #2	$104.72	9.874%	$115.0601	$115.06	$115.05	$115.10
Purchase #3	$182.94	4.824%	$191.765	$191.77	$191.75	$191.80
Purchase #4	$14.62	6.444%	$15.5621	$15.56	$15.55	$15.60
Purchase #5	$209.55	3.664%	$217.2279	$217.23	$217.25	$217.20
Purchase #6	$244.79	4.796%	$256.5301	$256.53	$256.55	$256.50
Purchase #7	$83.46	7.435%	$89.6653	$89.67	$89.65	$89.70
7 purchase totals =	$1,027.40		$1,091.5853	$1,091.59	$1,091.55	$1,091.70