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	$141.55	6.862%	$151.2632	$151.26	$151.25	$151.30
Purchase #2	$83.37	7.161%	$89.3401	$89.34	$89.35	$89.30
Purchase #3	$167.72	7.261%	$179.8981	$179.90	$179.90	$179.90
Purchase #4	$219.27	9.595%	$240.309	$240.31	$240.30	$240.30
Purchase #5	$11.69	9.823%	$12.8383	$12.84	$12.85	$12.80
Purchase #6	$211.83	12.321%	$237.9296	$237.93	$237.95	$237.90
Purchase #7	$140.52	13.830%	$159.9539	$159.95	$159.95	$160.00
7 purchase totals =	$975.95		$1,071.5322	$1,071.53	$1,071.55	$1,071.50