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	$62.25	7.757%	$67.0787	$67.08	$67.10	$67.10
Purchase #2	$175.55	8.481%	$190.4384	$190.44	$190.45	$190.40
Purchase #3	$198.55	10.275%	$218.951	$218.95	$218.95	$219.00
Purchase #4	$238.37	9.552%	$261.1391	$261.14	$261.15	$261.10
Purchase #5	$195.27	13.215%	$221.0749	$221.07	$221.05	$221.10
Purchase #6	$94.54	10.114%	$104.1018	$104.10	$104.10	$104.10
Purchase #7	$81.47	9.630%	$89.3156	$89.32	$89.30	$89.30
7 purchase totals =	$1,046.00		$1,152.0995	$1,152.10	$1,152.10	$1,152.10