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	$97.38	7.409%	$104.5949	$104.59	$104.60	$104.60
Purchase #2	$191.33	12.558%	$215.3572	$215.36	$215.35	$215.40
Purchase #3	$196.44	9.662%	$215.42	$215.42	$215.40	$215.40
Purchase #4	$170.47	6.473%	$181.5045	$181.50	$181.50	$181.50
Purchase #5	$91.81	6.203%	$97.505	$97.51	$97.50	$97.50
Purchase #6	$175.31	13.243%	$198.5263	$198.53	$198.55	$198.50
Purchase #7	$64.48	11.506%	$71.8991	$71.90	$71.90	$71.90
7 purchase totals =	$987.22		$1,084.8070	$1,084.81	$1,084.80	$1,084.80