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	$79.34	7.313%	$85.1421	$85.14	$85.15	$85.10
Purchase #2	$134.73	7.569%	$144.9277	$144.93	$144.95	$144.90
Purchase #3	$168.43	6.595%	$179.538	$179.54	$179.55	$179.50
Purchase #4	$25.97	7.825%	$28.0022	$28.00	$28.00	$28.00
Purchase #5	$215.97	11.713%	$241.2666	$241.27	$241.25	$241.30
Purchase #6	$198.52	3.397%	$205.2637	$205.26	$205.25	$205.30
Purchase #7	$55.34	7.263%	$59.3593	$59.36	$59.35	$59.40
7 purchase totals =	$878.30		$943.4996	$943.50	$943.50	$943.50