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	$92.97	3.104%	$95.8558	$95.86	$95.85	$95.90
Purchase #2	$73.64	7.170%	$78.92	$78.92	$78.90	$78.90
Purchase #3	$23.41	9.388%	$25.6077	$25.61	$25.60	$25.60
Purchase #4	$247.53	4.790%	$259.3867	$259.39	$259.40	$259.40
Purchase #5	$141.59	7.808%	$152.6453	$152.65	$152.65	$152.60
Purchase #6	$141.89	4.803%	$148.705	$148.71	$148.70	$148.70
Purchase #7	$74.72	3.359%	$77.2298	$77.23	$77.25	$77.20
7 purchase totals =	$795.75		$838.3503	$838.37	$838.35	$838.30