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	$49.75	6.409%	$52.9385	$52.94	$52.95	$52.90
Purchase #2	$11.37	8.443%	$12.33	$12.33	$12.35	$12.30
Purchase #3	$39.74	6.854%	$42.4638	$42.46	$42.45	$42.50
Purchase #4	$142.25	7.155%	$152.428	$152.43	$152.45	$152.40
Purchase #5	$239.98	12.171%	$269.188	$269.19	$269.20	$269.20
Purchase #6	$126.43	11.829%	$141.3854	$141.39	$141.40	$141.40
Purchase #7	$180.55	7.619%	$194.3061	$194.31	$194.30	$194.30
7 purchase totals =	$790.07		$865.0398	$865.05	$865.10	$865.00