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	$92.42	4.629%	$96.6981	$96.70	$96.70	$96.70
Purchase #2	$167.80	7.406%	$180.2273	$180.23	$180.25	$180.20
Purchase #3	$232.68	5.667%	$245.866	$245.87	$245.85	$245.90
Purchase #4	$81.90	9.213%	$89.4454	$89.45	$89.45	$89.40
Purchase #5	$79.82	12.215%	$89.57	$89.57	$89.55	$89.60
Purchase #6	$248.25	4.161%	$258.5797	$258.58	$258.60	$258.60
Purchase #7	$198.72	3.828%	$206.327	$206.33	$206.35	$206.30
7 purchase totals =	$1,101.59		$1,166.7135	$1,166.73	$1,166.75	$1,166.70